Cruz has and once even was rebuked by the Christians who just want to get along under the Muslim thumb. Trump is the new Christian martyr..go figure.
Cruz is a good man, and after he is Trumps VP, learning some of Trumps skills, he will be a really great President.
For now, it would be my guess that the people you mentioned think he can't get the job done. This job, half done, ends up with dead Christians.
FWIW, I don't think he can get it done either, and that isn't a slam, it's simply my judgment.