It won't last, because he's not socially conservative. He's either said nothing or given very mixed answers on social issues, eventually the socially conservative voters will shift to Cruz, Huckabee, or maybe Walker, Rubio, or Carson. Someone who actually agrees with them on issues.
You're implying white evangelicals are a thinking group of voters. These are the same people that gave their money to Peter Popoff. They have no principles. They'll have faith in Donald Trump.
Life must be really easy for you, huh? When you can simply write off a whole group of decent Americans simply because you disagree with them.