I know you just want to have your beer in peace without having to confront chanting fanatics, but one thing that sometimes works is to pull out your phone and start filming people. After a second, they think about all the people who have had a shit storm come down on them when a video goes viral and maybe the bartender would realize that it’s not great for business. A while back, I was in a taxi when an idiot road rager went nuts and was driving aggressively and yelling racist stuff at the driver. I pointed my phone at him and started filming and he immediately backed off.
As for Trumpism being a religion, it makes sense: it’s people believing that certain actions are going to benefit them without any evidence to support that belief. Say the magic words “Build the Wall!” and you will be happy.