The linked article has a nice tidy theory of "Evangelical voters".
Trump is drawing those voters who are Evangelical but don’t see themselves as “Evangelical voters.”In other words, they’re not imposing faith-based litmus tests on candidates, they don’t care about candidates’ personal lives, they’re less concerned with social issues, and they’re more in line with old-school Southern populists. Oh, and they really, truly don’t like being told what they “should” be doing and strongly dislike moral scolds — especially politically-correct moral scolds. Many of these voters were equally comfortable going for Clinton in 1996 and Bush in 2000.
Cruz is pulling more from the voters who define themselves as true-blue (I’m sorry, true-red) Evangelicals and who are craving someone who shows that he has the courage to confront the establishment and the liberal media without compromising one inch on core principle. If you’re talking to a voter who’s concerned first and foremost not just with a candidate’s faith but also with their moral and political consistency, then you’re likely talking to a Cruz voter. If you’re talking to someone who feels like the GOP has exploited Christians for votes, only to abandon the fight at the first sign of resistance, you’re likely talking to a Cruz voter.
Rubio, by contrast, is getting his share of voters who look primarily to a candidate’s faith, but he’s also drawing substantial numbers from Evangelicals who care deeply about a candidate’s manner. They want to see their candidate not just as a faithful Christian but as someone who can defend that faith in the public square in a particular way. They also tend to be more ambivalent about immigration — concerned about border enforcement, to be sure, but less closed to legalization. If you’re talking to an Evangelical who believes that their candidate can break down walls and expand the Republican constituency, you’re likely talking to a Rubio voter.Tidy, but I don't buy it. Sure, like most theories, I suspect you can find SOME people that this would explain, but I think it misses the core of the Trump phenomenon.
Conservative Christian voters and MANY others have been disappointed by Republican Presidential options in the cases of HW Bush, Dole, McCain and Romney. W was "better", but a LONG way from Reagan! Add to that, absolute disgust with Republican House and Senate, plus party leadership since Newt, and you have a case where while they DETEST the Democrats, they have at best a STRONG DISLIKE of the Republican establishment!
As one ex Congressman said at a meeting I was at, "You have no idea how corrupt Washington is. It is is probably hopeless, but the best we can hope for is a LONG SHOT that Trump will "shock the system" enough to right the ship, otherwise, we are going DOWN!"
After an effective decade** of Democrat rule, the conservative R's are DESPERATE! Their "strong dislike" for the Republican establishment is pretty much at DISGUST after 5 years of House control and a year of both House and Senate, anyone of a conservative bent can see that we have NOTHING to show for controlling one of the branches of government. As I cover below in **, I can understand the reality of what is happening, but I can ALSO understand how R's FEEL, as well as have extreme disgust for the leadership in both House and Senate. Yes, they are likely to lose, but at least they could LOSE WITH SOME CLASS!
This situation has given us TRUMP. Rubio is "establishment", which is NOT popular, Cruz is hated by the establishment and doesn't come across as somebody that can win -- therefore Trump. (Cruz is still my guy -- Trump could always shoot someone, if that would even matter).
**NOTE, when TP controls ONE branch of government, since they control the media, they effectively control it all. If a a Republican president attempts to stop Congress from acting, he is considered to have "shut down the government", be "partisan/ideological", and "not willing to govern". (see HW Bush vs congress for reference)
Reverse the situation with R's in control of congress and TP in the WH, and any attempt by congress to get anything done or block presidential action is "overreach, partisan, dangerous"! (see BO interactions with Republican Congress).