I have been thinking a lot about this. If I am to believe in some God, it should be the God I can see.
When I saw Slifer as a kid, in Yugioh season 2 episode 17, it was for the first time I have seen an actual God in glory.
I remember cheering "Kill them, Slifer, kill them!"
Later I learned that Slifer is one of three Egyptian Gods. In my mind, he is the coolest God among the three.
He is red and black, which are my favorite colors.
I am pretty sure Slifer would beat Christian God in battle. He could also beat muslim's Allah, I think.
No one ever seen Christian God or muslim god, but we have all seen Slifer. We know he is real. There are videos of him, and photos.
Slifer has two mouths, which make him look very cool.
He also has control of lightning and skies, and he is a dragon with large wings and long tail.
Plus, Slifer is Yugi's favorite God. Yugi is a good person. He fights for justice. So I am on the right track.