That's just the point though isn't it, he is a populist. He doesn't actually believe in anything from a political point of view, he is open to saying or doing anything. The guy identified as a Democrat but decided to run as a Republican because it was an easier path.
The whole 'ban Muslims' talk was just that, talk to win in the rabid Republican primaries and he changed his tune as soon as he needed to appeal to a wider crowd.
What he will actually do in power we really have no idea.