Truth, Tolerance, Certainty and Knowledge.
It is considered intolerant to say that one believes that someone else's deeply felt belief is false. This has become so rare that it has become shocking even coming from Pope Benedict. This seems to me to be a distaste for logic. It is hard to hold contradictory beliefs at the same time, so it is psychologically difficult (and I would guess dangerous) to try to agree with everyone's religion.
Yesterday, I thought maybe the secret is doubt. There is a difference between saying, for example, "I am Christian so I think that Mohammad was not a prophet" or "I am Moslem so I think Christ is not divine" or "I am atheist so neither" and saying "I am sure Mohammad was not a prophet". Logic does not prevent us from thinking that each of two contradictory claims might be true.
My problem is that I have no doubt that Christ was not divine and Mohammad was not a prophet and I don't want to admit that I am intolerant.
Now my only defense is that I don't think that I know that Christ was not divine, that is, my belief (which I hold without doubt) is not justified or proven. This is easy, because absolute knowledge is impossible. Justification or proof only exist within systems of justification or proof, so knowledge can be knowledge within the Christian faith or given faith in the scientific method or somethin, but it can't be just plain knowledge.
Another way I can be tolerant is to note that my atheism has a similar origin to the faith of the religious, that is I don't think that they made a mistake in reasoning which I didn't make. That is, I don't the that the cause of my belief is a valid proof that it is true.