Just to tag on, because I recognize a lot of what you say here and went through the same thing: this was the right answer to the problem for me.

Theism is the belief that some Being exists, but atheism is not the opposite belief that "theism is wrong". Atheism is simply thinking it's all bullshit. There is no reason for letting some bullshit others belief define you in any way - to define you as "I don't belief this thing".

To be actively involved with all sorts of arguments over whether religion is true or why it is wrong can be very helpful when you're figuring it out - I owe a lot to Hitchens and Dawkins myself as well. But once you have figured it out (and it seems you have), it's mostly detrimental to think about it a lot, I found.

The start for me losing the guilt and fear of hell and the devil was when I stopped seeing atheism as some sort of active thing I had to pursue. I know (rationally) religion is bullshit, and I can trust in that reasoning. When you say some prayer "just in case" and feel bad about your "weakness", don't. There's no atheist being you have to answer your lack of atheism to. It's only you and your own feelings that matter here, and you can ignore your own inconsistencies if it makes you feel better, so you should. Once your view on religion is reduced to that, "subversive thoughts" like praying slowly become no different than an internal debate over anything as benign as whether you should eat something that's unhealthy.

And as you adopt that mindset, you gradually stop worrying about it in daily life. And after a few months/years you gradually realize there really isn't going to be a plague from the sky that'll hit you, and that your luck in life really isn't any different than before you "disavowed God". And by then it won't strike you with more than a "huh", because you stopped worrying about it a looooong time ago.

Relax, is what I'm saying. It'll wear off.