When I first left, I became nondenominational "generic" Christian, back when I still thought that was something someone could really ever be.
Then, a friend challenged me to read the Bible again, but from the perspective that I was learning about this deity for the very first time. I accepted that challenge and only made it through chapter eleven of Genesis by sheer force of will. I was already atheist by the end of chapter nine.
I tend to think deeply about the why of my own internal processes and I have eventually arrived at this explanation:
If any deity is reality who has sufficient power to accomplish its intentions and who also intends for all humans to know it is reality, then, every human would already know that specific deity is reality, no theists (of any variety) would be killing any other humans over which deity is reality, no theist would see any need to advocate for such a deity, and I couldn't be atheist.
Therefore, observable reality confirms conclusively that at least no deity is reality in whom those two deity specifications coexist.
This obviously doesn't prevent any other propositions of deity, but does eliminate many already proposed deities from consideration as possibly being anything other than fictions. Any other propositions would need to be accompanied by explanation why the proposed deity ought to be regarded as reality rather than fiction, and why the proposed deity ought to be regarded as deity.