Yes John= David in this case, just as Yahweh= Allah, because BOTH religions pray ONLY to ONE God, the supreme God. If all 3 religions are in concensus that there is ONLY ONE Supreme God, then they must all pray to the same God. The individual differences in the religions may determine, however, the characteristics of that God.
Characteristics can't be determined mutually exclusively if they all pray to the same God.
Christians believe God has a Son.
Jews etc do not believe this. So, God has a son, yet he doesn't have a son, yet the Gods are the same.
The God of the Christians God didn't make a prophet out of mr. child molestor, yet the muslim god did, yet they are the same God?
It's all about conversions.