Religion cannot hurt other religions without corrupting and using its own to people. It abuses its own.  That is what we are looking at.

Just a word of caution.  The religion uses the religious label to control people so its own refers to those it imposes the label on or pretends the label belongs to. So by its own we mean those who are made to feel as if their belonging is actually true.  There is a sense in which you are your own person so if the religion is just a social construct or a pretence then there is no belonging to it.  I can have the case of money and believe it belongs to me and I to it and be wrong.

When a religion picks on its own
People of a religion killing their own has nothing to do with proving the religion is okay or good. The argument that Christians who kill Christians are thereby proving they are not being Christian is rubbish. The hint that Christianity is too good to hurt people is insulting. And it is nonsense to say a religion is proven good even if it persecutes its own but is bad if it persecutes others. And the argument is central if you wish to make out that religion is always good. It is always top of the list for commentators.
The common advice that if a bully picks on you you must try to see that it is all about the bully and is nothing in you is toxic. Why? Because the victim knows though she or he did not cause the bullying there is something about her or him as person that the bully reacts badly to. Religion sorts of exemplifies such advice when it seeks to blame the individual members of the religion and not the faith system. By faith system I mean the body of doctrine and religious practice and religious morality not the people. It is evil to blame the person to exonerate the faith. Moreover, religion does not ask that anybody accept that the faith is good and beautiful regardless of whether they believe or not. No religion hates the thought. To ask people to accept that religious faith and a religion is wonderful is trying to persuade them. If it were really that great it would not need the asking.

Tries to oppose and undermine truth
To create a mental disconnect between a person and her place in the world is also to create an emotional disconnect. To oppose truth willfully or unwilfully is to give evil people permission to harm. Why not if truth does not matter? If you condemn them you will make them worse for they will see you as hypocritical and unfair. The condemning makes you worse not better. A faith that causes evil to flourish is actually better than one that does not but which allows evil to flourish. When your faith allows the evil of others to flourish, it is worse than one that lets the evil in you flourish.
We are keen to pay no heed when members of our religion do evil as long as it is not us doing the evil. That is why Catholics stay in the Catholic Church despite its role in protecting and encouraging child abuse by priests. We tend to categorise people as good or evil instead of admitting that instead of being good or evil, those people are countless shades of gray. Some are darker than others.
Even if atheism and secularism sometimes lead to evil, we need them. We do not need religion so we cannot say, "Evil will happen anyway, so religion should be supported even if it leads to some evil or even if some of its members are bad."
Faith in the supernatural is giving tacit approval to doctrines and practices and religions that protect those who do harm in the name of faith and God and religion. You may keep your hands clean but your heart is far from clean.
People who make a supernatural claim and who tell you to make excuses if it seems to be false are trying to stop you from seeing that it is false if it is indeed false. They do not inspire trust.
Religion in manipulative fashion wants to be labelled as good
Religion defines itself in a way to make itself look good or at least to deflect being tarnished by the behaviour of its members and its lies. But a definition is only words and means nothing – it is the evidence that must define what something is. If a playschool advertised itself as perfectly and only good we would roar with laughter. But a religion can get away with it for it claims to be dealing with powers we do not understand that can avert human evil and destructiveness. It hides its dark dealings under the cloak of mystery.

A rock proves by its appearance and absence of personality that it is not a human being. See the point? It is not up to religion to define itself as good or indeed up to anybody. We must look at the evidence and proofs and follow those. They do the defining in a manner of speaking.

Messing with the definition of religion could be dangerous
Those who redefine religion as goodness are just being stupid and it is insane to imagine one faith is as good and realistic as another. Messing around with the definition of religion may have people deciding what is good and calling something religious if it agrees with that. That is why some ignoramuses say that it is unchristian of Christians to stop gay marriage. They define gay marriage as good and equate good and religious. Something you agree with morally is not turned into something religious just because you agree with it.
If Islam is a religion based around grave violations of human rights then to say it is not a religion is to claim the right to persecute it and deny it is religious persecution. Messing around with the definition opens the door to the likes of Donald Trump who say that Islam is not a religion but a political ideology with some religious trappings. Get the right definition instead of hurting human rights by equating religion with good or defining religion in a way that suits your own political objectives. If Islam is not a religion then why not say Catholicism is not a religion but just something else wearing a religious face?
The moral is you can define religion as whatever fits your idea of human rights and invite persecution against a particular religion by saying it is not a religion for it wants women chained to the sink and abortion rights banned. And saying it is only partly a religion is just as bad. The religion will not be bestowed the rights you give a religion if you define it as a half-religion or quasi-religion or pseudo-religion.