God is not "a priori" justified.

Yes we learn about God but that doesnt mean the concept wasnt already in our minds... To really know where it comes from you have to look at where the idea of religion began. It began in many different cultures in many different places meaning humans have the idea of god built into them not just instilled later in life

who is then?

Science and history are against you , leading to the conclusion that you are a priori going to reject whatever you don't like.

In the Beginning God: A Fresh Look at the Case for Original Monotheism
by Winfried Corduan

"What you should know about In the Beginning God is that the book is (a) based on serious and systematic scholarship; (b) walks you through the historical debate over High Gods step by step; (c) explains most of the key issues simply, though there are a few difficult stretches; (d) is often witty, even acerbic, in dialoguing with scholars whom Corduan thinks haven't done their homework, or fail to think clearly. And that is just about everybody in classical anthropology -- Tylor, Muller, Eliade, Otto, Durkheim, Radin, even Andrew Lang a few times, more gently -- except Corduan's hero, Wilhelm Schmidt. (And Corduan even corrects him on occasion.)
"

So much for opinion with nothing behind it. I suppose you know that a priori means"from the earlier" so what sense does it make to argue about God (who must be first is He is anything) when you are arguing in terms of what is prior.

You would sound good in a movie but without the popcorn I just have to think you have no idea what you are thinking.