Religion is based on alleged revelations from the divine. If those revelations which may take the form of scriptures, enable religious violence (eg by doing nothing about it to challenge it), condone the violence by praising those responsible, or command the violence in the name of God, then the religion is calling you to essential fanaticism or essential extremism. The extremism might be kept inside you but it is no less real. It is opening the door to accepting those in your religion who will murder and persecute others in the name of faith.
What makes it worse is that if God gives a revelation, it is only a revelation as far as those who receive the revelation are concerned. The revelation is given to a prophet. The prophet passes on a testimony that he got a revelation. It is not a revelation to anybody but the prophet. God gives a revelation to the prophet and the prophet gives a revelation that he got a revelation to you. It is his revelation he gives you not God's for God can only reveal directly. So it is the prophet you listen to not God even if God really spoke to the prophet. You might say God has no other way to give the revelation to you but second-hand. If so, then why do no prophets really prove their credentials? The justification for listening to them is weak. The prophet makes hugely important claims and gives no evidence that he should be believed. That is sick when it involves commands allegedly from God to murder people. Even if God really gave the commands, it does not get around the problem that men claiming to speak for God are condoning evil or commanding it. Even if those men speak for God, it does not follow that going against them means intentionally going against God. No decent God would ever reveal a religion or faith that gets involved in war even a just war. It contradicts God's own rule that we must prefer God to human ideas.
The problems when man's word is taken for God's are:
-It is not God's word at all. Errors stop you being able to make your own decisions properly and to be your own person.
-Man gets the honour of his word being taken for God's which is unfair.
-One religion has a different word of God to the others and this leads to errors and danger and division.
-Even if the word is God's, you are still making an idol of what man says. The problem is worse if God has not given this word.
-You are taking "God's" word for it that x and y and z are true - thus you will pay no attention to anything that tells you its wrong and you end up in a vicious circle and draw others into it too.
-You fail to worship God as he is. You only care about feeling good about taking man's word for it that God has spoken. This is about man not God and is about inventing a God to suit yourself.
People are often persecuted or put to death because of what religion they are thought to believe in. Usually the reason this happens is because the persecutors feel that they are not going to change anyway. They won't abandon their faith or consider a new one. If a religion is man-made, it is a terrible thing to join it when it puts you in danger. The religion is to blame for it as much as the persecutors. The religion is to blame because it is based on deception and error. It is to blame for it makes you immune to any data or evidence that the religion is nonsense or wrong or irresponsible or should be forsaken for a new one. It does this by telling you that there is some authority that tells you what to believe and do and this authority is right even if what it says seems insane because it knows better and sees the bigger picture. People who are not religious can be immune to data and truth too. But religion makes it worse. At least if you embrace the law of cause and effect and keep magic and divine revelations out of your thinking there is reasonable hope that you will come to your senses.
Also religion talks about karma or God both of which threaten you with bad things if you sin. When people are threatened with punishment, they tend to obey outwardly but inwardly they would disobey if they would get away with it. But surely if God wants you to obey willingly you will know that you can't please him with mere outward compliance? But if you think you obey willingly you could be fooling yourself. The threat of punishment makes such self-deception easier.
Our moral values never directly motivate us to do the right things. It is our emotional attachment to those values that does that. Thus it is dangerous if we help others because our hearts are on fire over Jesus. What is wrong with that? What is wrong with it is that Jesus is not the dying baby on the street. Your heart should be on fire for the baby not Jesus. If our feelings are so powerful, it is wrong for anybody to urge us to direct them towards a God or religion instead of the sufferer.
Why do even insincere people make huge effort to evangelise others? Because there is a massive buzz when people accept your testimony to the truth of absurdities and superstitions. People like to feel they have great control over others. They get the best buzz when people believe and follow harmful doctrines just because they influence them to. The worst religious charmers and charlatans do not do it for money at all. People don't like knowing they are liars - so if others seem to believe you it makes it easier for you to imagine that you believe your own lies.
Religion is bad for you because:

1) It does not allow you to think freely. Religion is based on the idea of dogma, teaching that you are obligated to accept and not deliberately question. Some say that atheism is religious - if it is it is not always religious. For a brand of atheism to be religion it would have to make a dogma of atheism. If religion really encouraged you to think for yourself then the pattern would be that each person moves from one religion to the other and religion would not be saying that changing dogma when new light comes along showing up faults in it, is wrong. Religion says you must forget your own mind and follow what God says for God knows better. This attitude is pro-persecution and sanctions deception – a thing religion is very good at.

Jesus condemned anyone who did not trust God. Offensively, he claimed that if you have even a bit of faith it can move mountains to bring about good meaning that the unbeliever cannot and is a blight on the planet. If you believe in God you have to trust him because you believe he is an all-good and all-powerful being. If Jesus had had any honesty he would have said that what such people are doing is doubting not God but what they are told about God. That cannot be wrong. Yet the Church and he make out that doubters or deniers are blasphemers for accusing God of lying! We all doubt so we know from experience that doubt is a part of the learning experience and there is no progress made without it so it is good not bad. If you will not doubt you will not see if you are wrong. A religion that forbids doubt is insincere and has stuff to hide.
Religion tends to take in new members and not inform them properly about what they are doing. For example, the Catholic Church does not tell new converts that the Bible is ridiculed by archaeologists and scientists and philosophers and teaches many vicious doctrines. They are not told things they have a right to know.

2) Religion sanctions persecution of those who disagree with it.

Religion says it is a sin not to believe in its doctrines. Jesus condemned those who did not believe in what he said. He said that his miracles proved to the people who knew him that he was telling the truth about speaking for what God wanted his people to believe. But what right had he to do that for there could have been people who they never heard of who were able to do better miracles? Whatever he did his miracles for it was not in the interest of truth. Jesus was certainly trying to persecute. He cannot complain then if his followers take up arms to destroy “heretics”.

3) Religion advocates cold-blooded hatred and dresses it up so that it still manages to come up smelling of roses. I am referring to its doctrine: “Hate the sin but love the sinner”.
The husband who beats his wife to a pulp because of her adultery will say it happened because he loves her. He will even believe that.
If you hate the sin you must hate the sinner for the sinner freely commits the sin. Sin is a quality a person has and you are your qualities. To hate your sin and wish evil on it is to wish evil on you and hate you. If a person hated your kindness you would know that is only another way of saying they hate you. Sin cannot be treated separately from the sinner for it reveals the sinner, it reveals what kind of person the sinner is. If you hate the sin you are inflicting pain on yourself because of somebody else’s sin and claiming that you love the person. But if you separate the sin from the person like that you are not loving the person for you are treating the person as if the person never sinned so that is hardly loving the person when sin is regarded as an enemy.
They say that God makes loving the sinner possible by some sort of miracle but that would be God doing the impossible – doing something contradictory. No other miracle would have any value as evidence for his power if he can do that one for his power would make no sense. Whatever miracles prove it is not God. When you become a sinner, being a sinner becomes the core of your sense of self. When somebody says they are gay they will argue that gay is them, their gayness is one of the things that define them as a person. They did not make themselves gay. So much more more does something you make yourself to be define you? To say nurses are bad is to say the people who are nurses are bad. Love the sinner and hate the sin is as silly as love the nurse and hate the woman who is the nurse. Or as silly as hate the bark but love the barking dog as a barking dog. The teaching that we must love the sinner and hate the sin because we are sinners ourselves suggests that hating the sinner is good but only if you are not a sinner! It involves wishing you were in a position to be able to hate the sinner!

4) Religion degrades human dignity. It says without being able to prove it that evil results in greater good because God makes sure of that. In fact it is better for us all to be totally evil than for one person to die yet they say death is good when it leads to a greater holiness which shows how totally perverse it is to condone the ways of God. We do not need the God hypothesis and it is pathologically barbaric to condone evil for it. To do that is to have no grounds for being against anyone going out of their way to condone the cruelty of some human tyrant.

5) We all recognise that to keep worrying about what others think of us is a sign of bad self-esteem. Yet one of the reasons people are keen on religion is that it is a weapon to control the vulnerable and confused. They are imprisoned at the fear of what others might think of them. You should feel good about doing whatever you think is right and be dictating your own life. To have a God in your life is to allow him to decide what is right and wrong for you and that is no different from worrying about the neighbours and wholly antithetical for self-esteem.

4) Religion takes rights it cannot have for it is just systems based on guesswork that is in opposition to facts.  Any facts it agrees with are agreed with only because its dogma permits them to be accepted or accepts them. They are not accepted because they are facts.

5) Religion stops you from being true to yourself. Unhappiness and lack of self-esteem arise from developing too many needs. Only go after important things like food and drink and shelter and friends for the simpler you keep things the easier it is for to be happy. Religion is not a need and to need it is to be a person with a disorder. Religion gives prayer and sacraments and divine revelations as remedies for the way it makes you feel which work temporarily and pull you down further so you need further fixes. It is meant to work the same as a drug addiction but often fails to program people successfully these days.

6) Religion encourages fear for if you were really free from fear you would not need religion. It uses tricks. Religious people are characterised by worry that society is going off the rails and was kept in check by religion in the good old days so they want religion to be as powerful now as it was then. The media feeds this by focusing on the bad in society. But that bad was always there. Religious believers use the fear to keep a hold on people. Christianity markets itself as being the only solution to many of society's problems. It moans that society is in tatters because there is nothing to unite people as a society meaning no religion. This is nonsense. We should not be united anyway in religion but be united as human beings. Christianity can only be an artificial solution. It's a diversion from the fact that we need to remember that other people are like other selves, just as conscious, just as vulnerable and just as uncertain as ourselves. These considerations should unite people better than people coming together to agree that Jesus is God or the Bible is his word or that the pope is infallible. Religion never unites people. What happens is that people see they are united by their common humanity and they use religion to express that. Religion is never a genuine unifying factor. The unification only happens in spite of the faith not because of it. Sooner or later disintegration happens. Consider how the Catholic Church broke up into separate sects all hating one another and how today liberal Catholics hate the traditional Catholics and are hellbent on pinning crimes on the pope.

7) Religion demands obedience even when you can see no reason to think that all of its morals are right. It is the idea that God knows better than us what is best for us and often makes rules we don't understand - ie like when the pope begged the Africans not to protect themselves from AIDS with condoms. So if he says it we must obey. Jesus said that we must love God with our whole heart and not love ourselves or anybody else that way and that this was the greatest commandment. His command to love neighbour as oneself is a restriction. You could love somebody perhaps slightly more than yourself but love that person less than God. That is disobedient and a sin and means you don't love God with all your heart. You have to obey him to love him that way. So love neighbour as yourself means: "Love God's rules about how you must be to your neighbour and yourself." It is not a warm thing at all. It is clinical and intimidating. But back to the real point. God comes first so he makes laws that glorify himself the best or get him the best glory and service from us. That should be our concern. We must obey his laws in the hope that he knows how best to promote himself best and get the most worship in this sinful world. We should not think of these laws being best for us for he matters. Our welfare is not the greatest commandment. The worship of God is the greatest commandment.

8) It tells you to serve God when you should be serving only yourself in a rational way. You cannot make others happy unless you respect yourself: only then can you be of benefit to them. Worship then is pro-irrationalism and therefore pro-evil and pro-cruelty. Good is used as a bait for the unwary in religion. If God is so great, then we should wish we were God above all things. The belief inflicts suffering on us. It is wanting suffering and trying to worsen the inevitable suffering of life.

9) Christianity is an example of a religion that has books that God wrote in which suffering is encouraged. It opposes self-esteem telling you to imagine that others are better than you (Philippians 2:3). When St Paul commanded that and the apostles accepted such a dishonest person as a witness to the resurrection that makes us question the resurrection when a lie like that was told for one person is as good as another. Christians are told to believe that they can no good without God helping them all the time for they are so useless (Romans 7). Verses that speak of confidence (Philippians 4:13; 1 Corinthians 11:1) say it comes from God so this confidence is not self-esteem but trusting that God will make good of you though you are useless. To teach that we are precious not because we think so but because God does (1 Peter 1:18,19) is really to say that what we think is useless. So if that is true how can we think we are precious because God thinks it because we have to think God thinks it? The teaching commands blind faith in dogma. If you don’t believe in thinking you cannot really believe in anything for belief is a kind of thinking so the teaching seeks to crush your self-love entirely and leave nothing only self-deception. Any faith that opposes self-esteem is evil.

Despite his visions, prayers and holiness and sufferings for God, St Paul still cried for deliverance from his body of death. He cried for someone to deliver him which means he wished that somebody would murder him. If a saint needed to do that how much more do we need to suffer. He claimed divine inspiration and the Church regards his writings as infallible so this is dangerous.
10) By exaggerating how wrong wrongdoing is, religion provokes our built in tendency to refuse to feel there is any good in the evil that people do. To suggest that even murder does some good makes people's blood boil. Religion invents sins such as missing Mass on Sunday or not celebrating Mass correctly if you are a priest. The atheist who does wrong cannot intend to hurt and offend God by it, so wrongdoing is worse as far as intention goes if you believe in God. So religion enhances evil.
11) Religion gives a delusional experience of meaning in life and insults the experience of those who feel their lives are wholly valuable to them despite religion playing little or no role in them.
It says you need to have a relationship with God and to see that you can have this relationship forever to have meaning in life. In fact, if you knew death was the end that would not stop you have a relationship with God now. And the fact is, even if death is the end and there is no God, any good you do is no less valuable. If you saved a baby's life, nothing can make that not have happened. If you don't feel your life has meaning after doing something so good then the problem is with your appreciation of good. It is too low. It is not a specifically religious problem. The problem is you. Religion can only help you delude yourself that you are not the problem.

Religion, especially Christianity, is bad news. It advocates submission to authority not commonsense. Even “moderate” religion has that in common with religious terrorists.