WMG / Love Tyrant

The God we see in the manga/show is not the first God.

He's Jesus. YHWH was the first, and gave up the seat to his son after Jesus finished his own stint on Earth. He looks much more like the typical depiction of Jesus than he does of God, his easy-going and all-loving nature match more with the New Testament God than the Old Testament God, and even his living in a Japanese-style house/room could be seen as evidence for this. His reason for sending Guri to Earth is pretty similar to (one of the) reasons God begat his son, as well.