"I don't care what you believe in, just believe in something" - Bishop in Serenity to Mal.
Even believing that there is no God, or believing that you don't need to believe in God, or believing that you could never know if there really is a God is a belief in something. Just because you don't believe in an all powerful Supreme Being, it doesn't mean that you don't have any belief at all.
When I left I had severe PTSD which was most commonly triggered when I contemplated my own death. My attacks were so severe that the muscles all over my entire body would lock up essentially paralyzing me. That put me in both a physically vulnerable position and in a position where I was stuck inside my own head. Initially I learned how to deal with and lessen the physical symptoms of my panic. Long term however I needed to figure out what I believed because it was the not having any belief that really caused the panic.
First, I trusted my instincts. I knew that I believe in possibility and always have but that I also need evidence. The only time I felt like God was a real being was when someone described him as energy. Well, everything is possible with energy. Everything in the universe exists because of energy. Energy makes the possibility of beings with more intelligence and more capabilities than humans very possible. Aliens are possible, angels are possible, and even Gods are possible. Does that mean that I own my existence to some greater being? No. Does that mean that some greater being could have created everything including that which eventually evovled into us? Sure. But that also doesn't mean that I owe my life, my liberty, my mind, my allegience, nor anything else to any other being. You don't normally have children and then expect them to be your slaves for the rest of their lives. But, do I believe that a greater being than myself is responsible for creating me? I don't care. I have what I needed. I don't need to "know" anything. I need to believe. And I do believe in all the possibilities.
I still struggle with my fear of dying even though it does get better with time. A few months ago I realized that my biggest problem with this fear is that the JWs set me up with the unrealistic expectation of 'knowing' what happens when we die. That isn't something that anyone actually can know and it isn't something that I need to know in order to have a wonderful life in the here and now. If I am always focused on my future death then I am still stuck in the JW mindset. This can be applied to belief as well. We don't need to know, but maybe we do need to believe in something. It doesn't have to be what everyone else believes in. Just find what you believe in and take comfort from that belief, whatever it may be.