Your final question asks

“Is it conceivable that the most convincing way to ground belief in God is through direct experiences of God,[…]”?

1. IMO history shows that belief in God is generally grounded in a religious education. And sometimes also in a personal experience, which the believer interprets according to the religious framework he/she has been socialized.

2. In any case, a belief in God is not the proof for the truth of the belief. If the believer makes a truth claim with his belief and wants to justify his belief, the claim needs to be checked in an independent and objective way.

   History shows that no objective check has been presented for the theist’s truth claim. But symmetrically, no objective check has been presented for the falseness of his truth claim.

Rebus sic stantibus (“as things stand”) one has to look for other criteria to decide between theism and atheism.

Your final question asks

“Is it conceivable that the most convincing way to ground belief in God is through direct experiences of God,[…]”?

1. IMO history shows that belief in God is generally grounded in a religious education. And sometimes also in a personal experience, which the believer interprets according to the religious framework in which he/she has been socialized.

2. In any case, a belief in God is not the proof for the truth of the belief. If the believer makes a truth claim with his belief and wants to justify his belief, the claim needs to be checked in an independent and objective way.

   History shows that no objective check has been presented for the theist’s truth claim. But symmetrically, no objective check has been presented for the falseness of his truth claim.

Rebus sic stantibus (“as things stand”) one has to look for other criteria to decide between theism and atheism.