1. No. God IS. Man tries to understand God.
2. The Jews believed in God in BC; after Christ, that belief extended to some of the Greeks and other Gentiles. The beliefs diverged beginning in Acts 2: during and after Pentecost. The expulsion of the Judaizers marked a significant point in the divergence. Paul correcting Peter on Christian versus Jewish practice was another milestone.
3. Not at first. The Jewish Apostles didn't really understand Him to be God at the beginning. If they did, they would not have huddled in fear of the Jews both after the Resurrection and after the Ascension at Pentecost. The writings I have seen indicate a growing awareness of the divinity of Christ and the Trinitarian formula of God which eventually culminated in Nicea.
Thank you, Mark, for your straightforward answer. I think I see what it is you are saying. In your previous post that caused me to ask the three simple questions, you said, “the nature of Nicene Trinitarianism was not understood by the Apostles and the early Church and most definitely not by Paul.” Now in your reply to me you say, “The Jewish Apostles didn’t really understand Him to be God at the beginning.” I assume by “Him” you mean Jesus.
There are several questions here. First, in regard to Nicene Trinitarianism, one could say on one level that of course the Apostles did not understand the nature of Nicene Trinitarianism. The phraseology of Nicaea did not come about until 325 A.D., and did so in response to specific errors, heresies, and misstatements of Christian doctrine. In the same way we could say that John Locke didn’t understand the nature of the U.S. Constitution and its separation of powers. And yet, it was John Locke’s writings about the separation of governmental powers that paved the way for the U. S. Constitution. Our founding fathers fashioned their phraseology in the Constitution and in the so-called Federalist Papers out of the writings of John Locke (and of course others). Would Locke have understood the Constitution and agreed with it? I rather suspect he would have had he lived another hundred years through all the events that helped to mold its arguments and then read it.
But on another level if we ask, did the Apostles understand God to be Triune, even though the word itself may never have crossed their minds, I see no reason to believe they didn’t. And I would say that in the case of the Apostle Paul specifically, he certainly did. Consider what he wrote to the Ephesians: “There is one body and one Spirit, just as you were called in one hope of your calling; one Lord, one faith, one baptism; one God and Father of all, who is above all, and through all, and in you all.” (Ephesians 4:4-6) How is this not to be see as the Nicene Creed in a nutshell? Otherwise, who is this Spirit, if not “the Holy Spirit, the Lord and Giver of life.” It is He Paul connects here to the calling of every Christian and thus the formation of the Church. Who is this Lord, if not the “one Lord Jesus Christ,” who Paul here connects with the “one faith”? And what is the “one faith” but that which follows immediately in the Nicene Creed, every bit of which, though phrased differently, can be found in Paul’s writings? And finally, who is the “one God and Father of all, who is above all, and through all, and in you all,” if not the “one God, the Father Almighty, Maker of heaven and earth”?
No, the words of Nicaea are not the words of St. Paul. But the thoughts are all certainly in line with what he wrote two and a half centuries earlier. That some later twisted Paul’s words and used them in support of an Arius or a Marcion does not in any way make Paul an Arian or Marcionite. So, the question is, had Paul lived long enough to experience the various heretical teachings and then read the Nicene Creed would he have understood and agreed with it. Again, I am quite sure the answer would be yes.