I am an atheist. Atheist, from a- "without" and theos "a god." Without a god. I am godless.
I am not merely agnostic. I think the nonexistence of gods can be known to the same degree of certainty as the nonexistence of centaurs or fairies or any other creatures of fable and myth. In each case, no matter the fervent desire of believers, the evidence is nil. We needn't honor the belief in things without (and against) evidence by labelling it with the comforting word faith; the more accurate word is gullibility.
I am not merely nonreligious. It is true I think religion strips the rich meaning people can give to their lives and replaces it with hours of wasted praise and prayer and devotion to injustice. It is certainly true I think immersion in religion ruins young minds and leads to embrace of the irrational, from creationism to global warming denial to the belief that people who believe differently deserve damnation. But my opposition to religion is the result, not the cause, of my godlessness.
I am not merely spiritual. I reject all supernatural explanations of reality and all beliefs in magic. I have no soul, and neither do you. There is no life-force. There is no qi. The universe is not god. There are no spiritual beings, no out-of-body-experiences, and the bright tunnel of light is what the misfiring of an oxygen-starved brain feels like. Nobody can read minds. Nobody can see the future. Nobody can bend spoons with thought. Nobody can heal with their hands. Nobody can cast spells.
There are no such things as ghosts.
This is it. Look around you. Clench your fists. There is matter and energy embedded in the quantum foam of spacetime, there is blood pumping through your veins, a sloppy biological primate brain shooting electrochemical signals through synapses flooded with neurotransmitters.
This is it.
A world without god is not hypothetical: we're in it now. Only we can make it a good one.