It all began with an argument; and the argument had to do with God, and God was the whole argument.
The argument had to do with God right from the start.
Every topic came up in the course of the argument; and if it hadn’t been for the argument, none of these topics would have been raised.
It was a very lively argument, and its liveliness made it very illuminating for everybody involved.
Ah, but the definite article nixes the translation ‘an’: it all began with the argument!
Pros + acc. isn’t really equivalent to peri + gen., either, even in weirdo Koine Greek. So maybe: “the argument was headed in the direction of God”? Not that “with” was ever a better rendering…