It may not be completely fair to judge the merits of a religion by the company it keeps, but it is consistent with human nature; after all, other than Constantine’s conversion, nothing helped spread Christianity like the martyrs. In light of that, the inevitable association of Christianity with irascible old Trump voters screaming about abortion, gay rights, and the wall isn’t exactly going to help spread the gospel among young people in this country. In the long run, the connection between Trump and the religious right is going to accelerate the decline in Christianity, bigly.
Much has been made over the years about the impact of the Christian right on American politics, but it may well be that the more significant change has run in the other direction, and not for the better. If Christians really want to take their country back, they would be well-advised to make more of an effort to win the intellectual and moral argument instead of imposing their will on the rest of us through the political process.