I think this election between Trump vs. Biden is more about personalities than anything else. At least with the non-affiliated with either party, swing voters, independents. You have obnoxious, uncouth vs. bland, stoic, humorless. Well both are humorless. Neither is charismatic. It's just a case of who you are tired of the most. Trump the reigning president, Biden the forever politician being senator and VP. Christian conservatives have always voted Republican, they're not in play. At least since Reagan and probably going back further.
The only voting block in play are the independents which at the moment Trump is losing. If Trump had a decent personality instead of that of a four year old spoiled brat, acted a bit presidential, he might not be losing independents or those tied to neither party. Sure, Trump will carry 90% of those who are Republicans, Biden 90% of those who are Democrats. That leaves roughly 40% of the electorate to choose who wins. With both major parties shrinking, just winning one's base isn't going to cut it. I have a feeling Trump will find that out.
I doubt issues and policy will have much play among independents, it will be which candidate they dislike the least or the candidate they least want to lose. As of today, Trump is disliked more and more independents want him gone. They just don't like him as a person. With his antics, name calling, temper tantrum throwing, creating needless feuds, it's not that hard to understand. Christians and barbarians aside.