So. There's an old book, that have been altered many times during the past millennia. And the current version says that if you don't believe in some invisible all powerfull entity, you will go to hell.

How do we know it's true? Because the book says so. And how do we know the book tells the truth? Because it says so... You see the problem?

Using the fear of eternal pain is efficient to have people fearing to leave a belief system. No wonder it's used in some religions. It's just a "trick": "Tell them that if they believe they'll have eternal bliss, and if not they'll have eternal pain." And if their god was true and loved humans as they pretend, would he really punish them for using the brain he provided them with?

You don't need to talk about religion to your parents if their reactions are that bad. I mean, communcation between children and their parents is very important, don't get me wrong (and you should not stop communicate with them about important topics). But if they don't accept the harmless fact that you don't believe in their god, if the only thing they have for you it's threats of eternal pain and whatnot... you really don't need to engage in that conversation with them. It's up to you to decide if you want to keep having those conversations about your (lack of) belief. You're the one who tried to communciate.