I think Cruz should agree with Trump where he agrees, and the diverge away from him in what should appeal to the Evangelicals. Most of the Evangelicals I know personally voted for Cruz in the presidential primary.
Cruz, in my opinion, is pretty horrible though. Involving his children in that Christmas commercial against Hillary was a total DISGRACE and down at the level of any of the lowest of the low regarding a bad example for children. Also, regarding the wife thing, Trump was right, Cruz “started it” when he went after Melania. Not that I excuse Trump at all for going after Cruz’s wife, but if you’re going to hate Trump for going after a wife of a candidate, then you have to hate Cruz too.
Edit: in case you don’t know the ad I’m talking about, see the video here: https://www.realclearpolitics.com/video/2015/12/19/ted_cruz_christmas_classics_it_was_the_night_before_the_shutdown.html