You can read about Trump and Holocaust denial in this recent news article: http://www.spiked-online.com/newsite/article/calling-trump-a-nazi-is-its-own-kind-of-holocaust-denial/19433#.WJzonRBNF4s
The following quote is from the news article:
President Trump has done some rash, bad things since he took power three weeks ago. But his critics have done something rasher. Something even more bereft of reason than Trump’s orders and tweets. Something more likely to stoke prejudice.
They’ve reduced the Holocaust to a meme.
They have used and abused the greatest crime in history to underscore their contempt for Trump, comparing him to Hitler, talking of his travel ban in the same breath as the Nazis’ persecution of Jews, warning darkly that ‘we know how this ends’. And in the process they’ve relativised the Holocaust. They’ve normalised it. They have dented its gravity and uniqueness by presenting it as a routine, recurring feeling in history that currently finds expression in ‘Trumpism’. They have turned the extermination of Europe’s Jews into an exclamation mark to their angst over Trump, and that is unforgivable. Morally, politically and historically, it is worse than anything Trump has done so far.
There is more than one way to deny the Holocaust. Some do it maliciously, with racist intent, arguing that the Holocaust is a hoax, an invention of Jews who wanted to secure their moral and political power in the postwar era. Others do it more thoughtlessly, with what they consider to be good intentions: they treat the Holocaust as a motif, to be wielded against any contemporary political idea or movement they find terrifying or simply don’t like. Bad people become ‘New Hitlers’, awful conflicts are said to echo the Holocaust. Holocaust dilution, we might call it. And it is a close, if sometimes unwitting, cousin of Holocaust denial.
Holocaust dilution has been rampant in media and radical circles over the past three weeks. In the overblown, sometimes even unhinged response to Trump, all sense of moral and political decorum, or basic reason, seems to have been abandoned. Journalists speak openly of ignoring Godwin’s Law in the Trump era — Godwin’s Law being the internet adage that if a web-based discussion about politics goes on long enough, someone will make a potty Hitler analogy. This grating BTL (‘below the line’) habit has now burst upwards, into actual commentary, and is embraced by the very hacks who for years sneered at the sad web-surfers who couldn’t go five minutes without typing ‘HITLER’.
End of quote from news article
Comparing someone to Hitler is the worst insult you can make.