I only was able to quit thanks to God intervening so I definitely attribute it to Him...
Yes some atheists do quit... My mother who is a hardcore atheist is a good example. Quit smoking for a few years, and later went back to it again. One can get a demon out even without God telling them so, sometimes people do realize with their brains that something isn't good. But that demon will come back, if not through the same door, then come back through another door with another vice, because the infirmity was never healed, and vacuum cannot defend the house. When such a person quits they start nagging and being cranky, or getting addicted to other things like food. Because the irritation and restlessness in the flesh (which is the reason they smoke) has never really been subdued. I've seen that first hand. So I disagree on that... About the claim how atheist successfully quit smoking without God, just like Christians do. But is this really a success?
Luke 11:24 When the unclean spirit is gone out of a man, he walketh through dry places, seeking rest; and finding none, he saith, I will return unto my house whence I came out.
Luke 11:25 And when he cometh, he findeth
it swept and garnished.
Luke 11:26 Then goeth he, and taketh
to him seven other spirits more wicked than himself; and they enter in, and dwell there: and the last
state of that man is worse than the first.