How do you know God is an objective reality outside the mind? Is that what you believe, or do you have proof?
My knowledge is best described by Summa Theologiae Ia, q. 2, a. 3, St. Thomas' classical proofs.
You imply that God is NOT objective reality? Are you absolutely sure of that?
The proofs are these:
First and foremost: The Creation - Yahweh declares explicitly that those who cannot see his handiwork in the creation are willfully blind.
Second: His Agents - His working of miracles and awesome demonstrations of power are transmitted to us by his declared agents.
Lastly, and most importantly to the world at large, generation to generation: The Prophecy - Yahweh is the only one declaring himself to be GOD that has left an indelible prophecy which, coming from the beginning, has declared the end. No other 'god' (to include Mohammed's) has done so. Every other one allows for amending the original declaration. Yahweh's words do not return to him empty. The proof is in the Prophecy.