I'll correct you, he has the Evangelical and Orthodox Conservative vote locked up.
That's about 20% of the primary electorate and 10% of the general electorate...locked up.
That's not to say he can win the rest...it's just that's it's never happened in modern times.
Actually, Trump has done quite well among Evangelicals.
http://www.theatlantic.com/politics/archive/2016/03/trumps-revolution-from-within/473430/
Evangelicals are a much more diverse thinking group than most people realize.