“From the Father, I’m going to send you the Helper, the Spirit of truth, who comes out from the Father. When the Helper arrives, he’ll be a witness about me.
The water of the flood is a picture of the way that baptism now saves you too. It doesn’t save you by washing the dirt off your body. Instead, it’s your way of promising God that you’ll keep a clear conscience by the same power that raised Jesus Christ from the dead.
We accept what humans say when they’re witnesses. But when God is a witness, what he says is much stronger evidence, because it’s God talking, and he’s talking about his own Son.