Well, if you believe in a god enough to make an enemy of them, they probably won’t stand for you trying to dissolve yourself on death and will put a lien on your soul.
If you are an atheist, then you aren’t going to have another god there to fight the lien, so by default, the deity will get it.
So your better bet would be to align yourself with a rival god who would be willing to fight for your soul upon death…
You really don’t want to be all alone in the afterlife, even if you plan to dissolve, you won’t be able to do it fast enough to not be captured. For one thing, most people have no ability to control anything once they die, so they can’t speed up their dissolution….