Godwin's Law (also known as Godwin's Rule of Nazi Analogies) is an adage that Mike Godwin formulated in 1990. The law states:
As an online discussion grows longer, the probability of a comparison involving Nazis or Hitler approaches one.
Godwin's Law does not question whether any particular reference or comparison to Hitler or the Nazis might be appropriate, but only asserts that one arising is increasingly probable. It is precisely because such a comparison or reference may sometimes be appropriate, Godwin has argued, that overuse of Nazi and Hitler comparisons should be avoided, because it robs the valid comparisons of their impact.
Although in one of its early forms Godwin's Law referred specifically to Usenet newsgroup discussions, the law is now applied to any threaded online discussion: electronic mailing lists, message boards, chat rooms, and more recently blog comment threads and wiki talk pages. Link
Some say that due to Godwin's Law that if you bring up the Nazis you automatically loose the debate. So unless unavoidable, my suggestion would be to not use the Nazis or Hitler to make a point in a debate.