Trump has switched party's like five times.
He's been a democrat twice, a republican twice an independent and for a time registered without a party.
He went republican this time because he knew he had no chance to get the nomination over Sanders and Clinton.
But Trump really has no party affiliation which you can see from his fighting with republicans, he is an opportunist. Although when you look at some of his policies you can see he is all over the board.
He is certainly not religious, he is not against banning guns as he did with the bump stock, he is most definitely not pro-war, he cares nothing about abortion.
What we see is him making a bunch of campaign promises to win an election, for the party he decided to run with, and keeping those but does he actually have any belief in them?
I don't think so, but he has to do it to maintain power.
Trump likes to be in power and will do whatever it takes to get that, had he had a shot in the democratic party he would have went that way instead, with different campaign promises that he would be fulfilling today.
Basically Trump is someone with no views, he is a representative of those who elect him which ultimately is what a true politician should be.
We elected him to do certain things and he is doing it very effectively but not out of beliefs held by him, he's doing it because he likes being president.
The only other president similar to this was Eisenhower who also had no party affiliation or deeply held beliefs, In fact both sides were courting him to be their nominee. He mused over this for a long time but eventually chose the republicans because he was military and felt they had a slightly stronger military belief. His actions after election were determined by the party that elected him, not by anything he believed profoundly in. He just wanted the presidency.