Some say that principles do not come first and practice is what matters. But to celebrate the rejection of principles or violence against principles mean you cannot object if people decide to put their bad principles into practice. Or if they create new bad principles. You don't say that the principle of paedophilia being bad is unimportant as long as people don't carry out acts of child sexual abuse. Your condemnation of their actions only makes you a hypocrite who tolerates their evil. Principles are not just rules but about people. For example, if you value truth you automatically value people's need for the truth and their right to it. Principles consider the bigger picture and look beyond pleasing some people to what is best for as many people as possible in the long-term. If you suffer for the truth it will pass and it is worse to give in to those who hate the truth.

Relativism is the view that whatever you think is the truth is the truth and everybody has their own truth. Moral relativism is the notion that you have a right to your moral opinion and that nobody should tell you your morality is immoral or wrong. It rejects the idea that anything is absolutely wrong. But it contradicts this by saying its always wrong to say relativism is wrong! It rejects the idea that morality is fact-based - or objective which means the same thing. But as we cannot stop thinking of moral right and moral wrong as facts and they can't stop presenting themselves as facts the relativist is only trading objective morality for an invented objective morality.
Relativism accuses objective morality of being intolerance but is itself intolerance. It condemns the view that morality is objective and real. It is not a proper response to the problem of tolerance. The pope speaks of the dictatorship of relativism which regards the person who rejects relativism as intolerant and evil. If a moral fact is a fact then tolerance demands you accept it. The fact is not intolerant - it is just a default. It is not intolerant for a tree to be a tree not a pansy. Its just a default - the way it is.
The modern adage, "You have a right to your opinion/belief" is used by those who think they should think or believe whatever they WANT rather than think or believe whatever seems TRUE. Its a revolting misuse based on the wish to become immune to rational argument or persuasion. The only reason you have a right to your belief or opinion is that you use belief and opinion to find the truth or to improve your knowledge and accuracy. To say you have the right to believe or think what you want is ridiculous. It is not about what you want and you have no right to deceive people that it is. Grow up!
The person who tries to believe what he wants without regard to what is true is being intolerant of the fact that belief is based on evidence. He is not being fair or honest in this. He is not being supportive or tolerant towards those who want to base belief on good reasons. He will fear and tend to be bigoted towards those who endanger the facade he has created.
People say they have a right to their beliefs and opinions. That is actually a half truth. The correct thing is to say you have a right to your beliefs and opinions as long as you see them as helps on the journey to truth. If you say you have a right to your beliefs and opinions without any concern for truth then you are not being fair. Fairness is based on what is true. The person who sees the truth and calls it a lie is being unfair.
A person can claim to be a moral absolutist or to believe in an objective morality. But a relativist can do that too for they are essentially amoral. It is probably safe to hold that as Christians are not that obedient to their version of God that they are relativists and not admitting it. The Epistle of James says it is only the remarkably religious and obedient who can be considered to be real people of faith.

Decide: morality is either really true (objective morality) or you can make it really true (relativism). Relativism trades objective morality for another objective morality that you make up. Pure relativists do not exist - they just are relativists when it suits them.