I agree that Evangelicals are likely focused on implementing their policies, and because Trump's an outsider, they trust he'll do what they want. So in effect, they're exploiting his mental disorder (his narcissistic desire for attention).

But the idolatry is baked into their theology now. By worshiping God as they do, indirectly they elevate Trump, deeming him a special agent of the Almighty. Especially after the assassination attempt, they think he's protected by God.