How to debate a Christian

[RAD]

Hello, I am an atheist, and I love to challenge the faith of some people around me with the hope that maybe with a successful debate I can help some of them see how useless and harmful the religious institutions are.

I don't disagree at all, but this fact proves nothing about Jesus anymore than the argument people who believe in him behave better. You don't seem to grasp that you rown argument is equallly as useless

I had some success stories but most of the time religious people avoid conversation about this topic and just change the subject.

I don't. Atheists supply most of the red herrings in my discussions with them

This is one problem, I understand that for some people changing their beliefs is useless and harmful, if the stories from religion help them in their life and they can function like this without troubling others, okay, I leave them alone and try to understand them.

It's called freedom of religion

Some simply don't want or can't understand new ideas related to religion, there is mostly nothing that can be done about those.

I've noticed the same thing

But some people don't benefit from belief in a god, and makes them in general more inefficient and more dangerous in their daily lives, and they have enough intelligence to grasp new ideas and maybe transform themselves for the better but are jamming themselves,

I can't imagine how I could have had a better more productive and creative life than I do. Neither could Isaac Newton I suspect, or Bacon, or Locke, whom Jefferson called the three greatest men in the world. (All Christians). You do a lot of pigeonholing in this post BTW

making religion a sensitive subject and want to avoid it. I want to know some methods on how I can penetrate this shell

Make an argument that doesn't employ logical fallacies?

And another problem is the text they use to close the conversation. Most of them are ignorable, but there is one that I don't feel that I can answer efficiently yet, and that is :"You didn't read the Bible so you can't talk about this subject". And the truth is I started to read this book a couple of years ago especially for this but I couldn't even finish Genesis, because its so silly, cruel, and simple that I didn't have the patience and stomach to continue, all that killing, incest, and that cruel, not so intelligent god were too much for me. So how can I answer to this statement so that I can continue on this subject?

False in one part so false in all is a formal fallacy, which you just committed. If only Mark is true, and all the rest is false, you have an intellectual obligation to change your worldview. Right?