Side note on the "they died for it => it's true" sophistry.
"It is so little true that martyrs offer any support to the truth of a cause that I am inclined to deny that any martyr has ever had anything to do with the truth at all. In the very tone in which a martyr flings what he fancies to be true at the head of the world there appears so low a grade of intellectual honesty and such insensibility to the problem of "truth," that it is never necessary to refute him. Truth is not something that one man has and another man has not: at best, only peasants, or peasant apostles like Luther, can think of truth in any such way. One may rest assured that the greater the degree of a man's intellectual conscience the greater will be his modesty, his discretion, on this point. To know in five cases, and to refuse, with delicacy, to know anything further . . . "Truth," as the word is understood by every prophet, every sectarian, every free-thinker, every Socialist and every churchman, is simply a complete proof that not even a beginning has been made in the intellectual discipline and self-control that are necessary to the unearthing of even the smallest truth.--The deaths of the martyrs, it may be said in passing, have been misfortunes of history: they have misled . . . The conclusion that all idiots, women and plebeians come to, that there must be something in a cause for which any one goes to his death (or which, as under primitive Christianity, sets off epidemics of death-seeking)--this conclusion has been an unspeakable drag upon the testing of facts, upon the whole spirit of inquiry and investigation. The martyrs have damaged the truth. . . . Even to this day the crude fact of persecution is enough to give an honourable name to the most empty sort of sectarianism.--But why? Is the worth of a cause altered by the fact that some one had laid down his life for it?--An error that becomes honourable is simply an error that has acquired one seductive charm the more: do you suppose, Messrs. Theologians, that we shall give you the chance to be martyred for your lies?--One best disposes of a cause by respectfully putting it on ice--that is also the best way to dispose of theologians. . . . This was precisely the world-historical stupidity of all the persecutors: that they gave the appearance of honour to the cause they opposed--that they made it a present of the fascination of martyrdom. . . .Women are still on their knees before an error because they have been told that some one died on the cross for it. Is the cross, then, an argument?--"
Friedrich Nietzsche, The Antichrist