In reality, after I had left fundamentalist Christianity, I had entered into much more of a no-man's-land of
agnosticism, where for about 20 years I didn't really believe nor disbelieve in the existence of God. I just didn't really tackle the question and left it open ended.
But then came a moment where I took a stance and said, "I do not believe that," and took a hard stance. That happened at a specific moment for me, watching the PBS special,
The Shape of Life, where I first really learned about how evolution worked. It was liberating. I no longer needed to hang onto the idea of God to explain the magic of nature. That was the birth of my atheism.
Now the motivation behind that, which I personally believe is what is behind most positive stances on the question of God which atheism proclaims, is to be able to
grow beyond superstitions and ignorance in the pursuit of the truth and knowledge, and to move beyond this 'not knowing' position which left me stuck or not addressing the deeper question of existence, or the nature of Ultimate Reality, as Paul Tillich termed it well.
It specifically and deliberately cleared the table of distractions to dig in and address the question. It gets rid of the debris that clutters the landscape, deeming it as unfit to be considered seriously on the playing field of modern knowledge. "God did it" answers do no suffice when being honest, nor did just putting the question on the backburner of agnosticism suffice. Atheism
empowered me to look at the question of Reality without fear.
I have now managed to move beyond that atheism now in much the same way I grew beyond theism, as well as agnosticism which itself centers around the same image of a mythic-literal deity question, where I now find no incompatibility between a spiritual faith and reason, doing no violence to either. I see theism, atheism, and agnosticism as all centered around the same thing, and doing the same 'this and not that' violence to each other in some fashion or another. They all view the question of God through the same lens.
I found this quote from reading Sri Aurobindo years ago that really struck me, and largely speaks my thoughts on this today:
"It is necessary, therefore, that advancing Knowledge should base herself on a clear, pure and disciplined intellect. It is necessary, too, that she should correct her errors sometimes by a return to the restraint of sensible fact, the concrete realities of the physical world. The touch of Earth is always reinvigorating to the son of Earth, even when he seeks a supraphysical Knowledge. It may even be said that the supraphysical can only be really mastered in its fullness – to its heights we can always search– when we keep our feet firmly on the physical. “Earth is His footing,” says the Upanishad whenever it imagines the Self that manifests in the universe. And it is certainly the fact the wider we extend and the surer we make our knowledge of the physical world, the wider and surer becomes our foundation for the higher knowledge, even for the highest, even for the Brahmavidya.
In emerging, therefore, out of the materialistic period of human Knowledge we must be careful that we do not rashly condemn what we are leaving or throw away even one tittle of its gains, before we can summon perceptions and powers that are well grasped and secure, to occupy their place. Rather we shall observe with respect and wonder the work that Atheism had done for the Divine and admire the services that Agnosticism has rendered in preparing the illimitable increase of knowledge. In our world error is continually the handmaid and pathfinder of Truth; for error is really a half-truth that stumbles because of its limitations; often it is Truth that wears a disguise in order to arrive unobserved near to its goal. Well, if it could always be, as it has been in the great period we are leaving, the faithful handmaid, severe, conscientious, clean-handed, luminous within its limits, a half-truth and not a reckless and presumptuous aberration."
~Sri Aurobindo, The Life Divine, pg 12,13