The core sentence in the article Varian posted a link to, and which narrowly answers the question in the OP is the following:
Many evangelicals have followed Trump: because he has implemented pro-life policies during his presidency. He also endorsed support for Israel, religious liberty and conservative judges.
The USA, from the start was a place of refuge for those whose religious beliefs were unacceptable in their home societies, whether you were a protestant radical or had an entirely new religion of their own devising (Christian Scientist, Church of the latterday Saints and some of the larger groups. Many cults that followed. Religon is part of the foundation of the country.
The USA is a large country with wildernesses and backwoods we cannot even imagine, so if people do not like what you believe or teach, there is also somewhere else to go. The less these conservative groups have to live close to non-members, societies, the more set in their ways they become.
Why do God and Guns go together because many of these groups live in these far west wildernesses and vast empty spaces, where, in the past guns were essential to eat and to stay alive when bad men arive, there are no police or the nearest policeman is 100 miles away.
Donald Trump is not immoral, he is amoral . He wouldn't recognise a moral if it picked up a stick and poked him in the eye.