Kinda hard to debate with religious folks because they're so confident and are 100% sure of what they say most of the time withouth checking both perspectives. I've had debates with my parents and they flip shit when I point out my view, it's pathethic.
Ok so here it goes. You most of the time born into it and grow up with it. After this it's hard to admit/accept that you were wrong for so long so you steak to the religion. There is actually a book about this (idk if it was translated to English though)
I've had this feeling when I was religious. I know what it's like to be closed-minded. As I grew up more and became more mature, I started seeing more in this world and it changed me completely.
You can't convince someone to change their beliefs, only they can choose to change their own. Take he high road, don't insult them, and don't give them anything to attack you with.
I'm a disbeliever and I can say that I'm more hopeful than the person that believes that if they eat too much, do too little, get really angry sometimes, want what someone else has, are extremely satisfied with themselves, have too many sexual partners, and/or are good at taking advantage of capitalism, they will suffer the most terrible pain imaginable for all of eternity, forever and ever burning and tormented because of actions they did for what would eventually be an infinitely small part of their existence.