People think he is the antichrist because he promotes vaccines and because there are multiple quotes of him where he explains that he wants to reduce the world's population. By raising the standard of living and giving healthcare to the poor, which empirically seem to cause lower birth rates, but lots of nutjobs assume he tests weaponized vaccines or something like that. And people are distrusting of people who appear too altruistic in general, thinking it's some kind of con (and often they are right).