What is truth? Is it relative? If something is true for you, would it also be true for me? There is quite often some confusion between what truth is and what a belief is. Most of the proponents of the idea of relativity of truth make the argument you aren't being tolerant if you believe something untrue to them may be true for others, or vice versa. In this case there is a confusion over the definition of tolerance. Tolerance is tolerating people whose beliefs are not true (or those who hold beliefs you think are untrue). Beliefs are true according to reality making them true or not, so it doesn't matter what you believe is true, truth is absolute. Just because someone's beliefs are false presents no reason for them to be persecuted or unaccepted as people – that is tolerance. You might attempt to persuade someone whose beliefs are not true to believe in something true, but that would not be an exercise in intolerance, it would be an attempt at persuasion. So we shouldn't explain tolerance as acceptance of any belief as true, that makes truth not a matter of they way the world really is... and that whole line of reasoning is all a big mistake.

Tolerance is a mater of not taking the truth of a person's belief to be a reason for tolerating that person or not. Tolerance has nothing to do with the truth of a person's beliefs. Some people think philosophy creates an atmosphere of questioning truth wherein we arrive at relativistic conclusions, and nothing is further from the truth. Philosophers are quite happy with truth, they think the truth is objective, and the misunderstandings of relativistic views of truth arise as confusion of words. Questioning is a way to get you thinking, and questioning something doesn't necessarily imply you doubt something. For example, there might erupt a new activist group that springs up somewhere collectively agreeing the Earth is flat. They could argue how all their experiences as far as they were concerned created this truth for them. However, clearly we understand what they call “truth” is merely a false belief that doesn't conform with reality. And it would not be an act of intolerance to attempt to persuade them to believe the truth.