Let me state this right from the start: I think Donald Trump is a racist, a sexist, and is firmly committed to a misguided nationalism. I think it's a mistake for Christians to go out of their way to vote for a person like Donald Trump. But, given the alternative, I also understand why some feel forced to do just that. However, I think it's wrong — and not just a mistake — for Christians to publicly support a morally abhorrent person like Donald Trump (and to encourage others to do the same).
As soon as it became clear that Trump was not just a side-show, but a real contender for the nomination, I have been firmly committed to the Never Trump cause. Today I am only more firmly committed to it.
With all of that said, trying to sway people away from Trump by comparing his rise to Hitler's is not at all helpful. Donald Trump is not Hitler and could not govern as Hitler did. He cannot wreck America like Hitler wrecked Germany.
Sometimes people will say things like, "Hitler came to power through democratic processes" but that's only half-true. Really, it's less than half-true, especially when compared to America. It's true that the Nazi party won a significant number of seats in the 1932 federal election, but it wasn't enough to form a majority government. Germans did not "elect" Hitler to office. Instead, Hitler used President Hindenburg's need to form a coalition government to orchestrate getting appointed Chancellor. Shortly after that he exercised various emergency powers that allowed his Nazi supporters to suppress various rival political parties (including the actual assassination of individuals who were prominent in those parties).
Why would the German populace allow something like this to happen? That's not an easy question to answer and I'm sure that if you asked a dozen different historian they'd give you (at least) a dozen different answers. But as things relate to this election, it's worth noting a couple of things that at least contributed to Hitler's rise to power. As we'll see, a number of significant differences between Nazi Germany and a potential Trump America need to be highlighted.
First, when Hitler came to power, that democratic form government had only existed for about fifteen years — it was formed as a result of Germany's defeat in the first World War. Many actually believed that pro-democracy revolutionaries were the reason the war was lost (this was the famous "stab in the back" that Hitler often spoke of when he first began his quest for power). Hitler didn't dissolve a democracy that was well-established in the minds of Germans. In fact, the Communists were one of the largest groups opposed to Hitler's rise and, as you can imagine, they weren't exactly pro-democracy.
Second, after their defeat and the signing of the Treaty of Versailles, Germany was in complete disarray. Unemployment was high, inflation couldn't be kept under control, and there was no indication that things would get better any time soon. Many began to believe that what Germany needed was another strong leader to come in and fix the problems the country was facing. There was no principled allegiance to the importance of democracy. The democratically-led government is exactly what many people blamed for Germany's wide-ranging problems.
There is a lot more that could be said on this, but I think this is enough to make my point. Neither of the above apply to America today. American democracy is now well-established and not even someone like Trump can come in and wreck that.
The American populace would never allow a president to try and abuse individual rights and liberties in the way that Hitler had to abuse them to keep increasing his power. It's absurd to think that either political party would let Trump do the same sorts of things that Hitler did, so it's not helpful to try and scare people away from Trump by comparing his coming to power with Hitler's. Doing so only muddies the waters when attempting to point out Trump's many actual faults.
There are two quick final points to make. First, the similarities that do exist between Hitler and Trump (racism, sexism, rampant nationalism) only serve to further emphasize the point I made at the beginning —Trump is a really terrible person. This is why it's so easy to make the misguided comparisons between Hitler's rule and a Trump presidency. It's also why Christians are unwise to publicly associate themselves with him.
Second, and finally, just as Americans won't allow Trump to wreck our great nation, the same can be said of Clinton. It's my deep and abiding belief in the Constitution and my fellow Americans that keeps me from falling into the trap of thinking that I must vote for Trump because Clinton would forever ruin America. If we Americans were capable of defeating the actual Hitler (along with Mussolini and Hirohito), then I'm pretty sure we can figure out a way to deal with another Clinton in the White House.