"If you don’t understand how something works, never mind: just give up and say God did it. You don’t know how the nerve impulse works? Good! You don’t understand how memories are laid down in the brain? Excellent! Is photosynthesis a bafflingly complex process? Wonderful! Please don’t go to work on the problem, just give up, and appeal to God. Dear scientist, don’t work on your mysteries. Bring us your mysteries, for we can use them. Don’t squander precious ignorance by researching it away. We need those glorious gaps as a last refuge for God." - Richard Dawkins
There is only one God left, and that is the God that exists in scientific gaps. And, as science advances, the scientific gaps become smaller and smaller, consequently making God smaller and smaller — until he eventually disappears.
Let’s start our analysis back on ancient times:
Throughout most of recorded history, the sun was believed to be a deity. It’s understandable: since the sun was, and still is, our main source of light and heat, primitive humans placed immense value on it. Scared of those times when big, dark clouds covered the sky, or when it rained, or even during eclipses, ancient humans elevated the sun to the status of a deity and prayed to it in hopes that the light would come back and shine upon them. The Ancient Greeks thought that the sun was the God “Helios”, a deity that rode a fiery, golden chariot every day. Helios would start his journey on his chariot, driven by four horses, on the east and would finish on the west. The Aztecs, on the other hand, worshiped Huitzilopochtli, their chief deity. They believed Huitzilopochtli to be the God of the sun and war. The Aztecs believed that the world could end on any day unless they kept the Sun alive — the way to keep him alive was by offering him human sacrifices. Helios and Huitzilopochtli are not the only Gods of the sun, others include Apollo, Aurora, Beiwe, Hors, Usil, and Saule, to name a few.
Indeed, this type of behavior was not exclusive to the sun; thunder, waves, the moon, and many other natural things were believed to be either Gods or controlled by Gods. In the case of thunder and lighting, humans believed that weather was controlled by Zeus, Thor, Ukko, Tezcatlipoca, Yu Shi, Jupiter, Chaac, or Indra. In the case of water, it was controlled by Poseidon, Neptune, Njord, Duberdicus, Lir, Acionna, or Laume. As you can imagine, ancient humans invented and worshipped thousands of Gods for nearly everything. These Gods that humans had invented stemmed from their lack of understanding or fear of the unknown.
But now, as science progressed by scientific inquiry, we have plenty of natural explanations.
We now know that the sun is just a big star, mostly of hydrogen and helium, that emits electromagnetic radiation. We know why there are clouds: the sun’s heat turns water (from oceans, plants, or soil) into vapor by breaking the bonds that hold water molecules together, which then ascends into the air, where the low temperature cools the molecules and changes them into thin droplets by causing it to condense with atmospheric dust. We know why there are dark clouds: as the cloud gets denser and thicker, less light can penetrate it. We know why there’s lighting: small bits of frozen droplets bump into each other while moving, which results in an electric charge being created, and then, suddenly, a negative charge connects with a positive one. We also know that there are eclipses due to the elliptical orbit of the moon.
As science progressed and explained these things, Gods stopped existing. Huitzilopochtli no longer exists. Neither does Helios, Thor, or Acionna. Of course, these Gods never existed — people just stopped believing in them. As science grew, the need for a God to explain certain phenomena diminished.
Science is evermore increasing and piling up more and more evidence about the real, observable world. There is no longer a need to put your trust in the supernatural when the natural explanation exists. At the starting point of human civilization, plenty of gods were needed. But as science advanced, Gods started disappearing. We are now at a point in time where every God that ever existed has been disposed of — all but one.
As Richard Dawkins put it, “we are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further.”
There is only one scientific gap remaining: “How did everything start?” Science doesn’t yet have an answer for that and that’s why a belief in God is mostly not completely irrational. But experience tells us that this last God will cease to exist, just like every other one, as science expands.