First things first, if they are stating things like they would commit murder or rape, I would assume they are full of it. I’d call that bluff, that’s basically argumentum ad baculum. Threatening yourself into your religion by making statements like that is just ridiculous. Also trying to persuade others to join you or accept your stance by threats of violence isn’t acceptable.
Because god isn’t real you would throw away your family, relationships, your job, your cars, your comfortable life to spend it dead or in a jail cell? Bunk bunk bunk.
Also if that is their argument, tell them to prove it then. That which is stated with no evidence can be dismissed with no evidence. It’s a powerless person trying to exert some form of power by claiming they have some unseen power lying in wait.
Don’t be threatened into accepting them, because they might do “something”.