You don't because they're being disingenuous and inventing ways to dislike him. Their same logic often doesn't apply to the other candidate. That's youth though. I was one of the Nader kids that thought I was taking the higher road between two evils. I also voted for Perot because he funded his own election. I was a problem voter, not a solution, and finally saw that I was really only getting the worst evil elected, so to hell with that.
Ask them questions like how hard would it be to keep a book and movie deal covered up, along with the promises of instant fame, money and celebrity were certain? And in a world where everything is surveilled, especially one of the the highest positions in the world, how would that play out? And then start asking them when did they begin having these concerns and why, with nothing pointing that they were indeed accurate, since it's not been revealed. Isn't that the meaning of faith based? Where do they get their information, which can be debunked pretty quickly since everything is connected somewhere.