The answer is racism. They think white people like themselves are the most discriminated in society and therefore Trump is the only one who will protect them.
The piece notes: "Fully 50 percent of white evangelical respondents ... reported feeling they face discrimination that’s comparable to, or even higher than, the discrimination they believe Muslim Americans face.... White evangelicals fear losing racial status. White evangelicals’ perceptions they’re the targets of discrimination -- more so than other groups -- influence far more than simply their votes for Trump."
It's worth noting these people are also strongly anti-LGBT and anti-marriage equality. They seem to be anti anyone who is different than them.
Their hate grows out of fear and anxiety. One could safely argue that their fear and anxiety is irrational.
They're blinded and crazed by hate.