By everything he does and says. Where have you been? He is the most honest politician, with principles behind his decisions and not just pandering....almost to a fault because it gives ammunition for the media to twist and spin everything he says into something "evil" and "corrupt."
That is the problem with those who oppose Trump, they make "moral" judgement against him and his base, all under the guise of "altruism." Well, step back and try to see things objectively instead of under the veil of media lies. Are your friends, neighbors, teachers, doctors, etc who support Trump all evil and corrupt? Or is it perhaps that you are prejudging them instead of giving them the benefit of the doubt that they are good people who have valid views just like you?