Darryl,
. I’m not sure if you are asking for a reply to your first set of questions or not, but will assume that you asked for answers to be given to what you have posted.
. As religion is seen as one continuous unfoldment from the Baha’i perspective, I suppose that it started with Adam, or before, and continued with Noah, Abraham, Moses, Jesus, Muhammad, the Bab (in 1844), and Baha’u’llah (in 1863)
. God was surely present at the foundation of Christianity, as well as Judaism, etc.
. As to the early Church, the Jews also had an early Church, to which they might yet ask:
“Were the Christians there at the time of Abraham?”
“Were they there at Mt Sinai?”
“Were they there when Moses parted the Red Sea?”
. I think the answer would be in the affirmative, in that those who have believed in God at the time of these chronological events are one and the same set of believers, and fully identify with all of those who followed, suffered, and endured for the sake of the Cause of God, regardless of the name:
. “And thou shalt be called by a New Name, which the Mouth of the Lord shall utter” Isaiah 62:2