Well done on your efforts with your dad, but knowing people like him, the only change happening will come from him. I've noticed over decades that most people have a thing about being right. They fight so hard to hold onto ideas that just don't work because there's something behind it they really fear - that's being wrong.
The belief has nothing to do with it. Politics, science, Alien abduction - it doesn't matter.
There are people out there that still believe Bernie Madoff was a good guy who was misunderstood and never intended to harm anyone.
Once they made that choice that Trump would make America Great again and went about telling the world that - there's no way he or anyone else can take those words back.
I'm willing to bet that the Captain of the Titanic spent his last moments on earth thinking - couldn't be an iceberg, just couldn't.
Take care.