I don't know. I think presidents need to be more open about their faith and actually attend church, but Trump did not go to the church to pray or make a statement calling for unity (as we're all God's children). That was not the time for a political stunt, and I really don't like the Bible being used as one.
I can't vote for Biden because of abortion, but I'm starting to question whether I can vote for Trump again (that's not to say that I've come to the conclusion that I can't, because I still don't know). I suspect that similar thoughts are going through the minds of a lot of Christians right now, especially those who only mildly supported Trump to begin with.
I totally get why you can't vote for Biden, but maybe you should vote third party or leave the Presidential slot blank or write someone in if you really feel disgusted with Trump. Trump's not entitled to your vote and TN's not going to decide the election.