When you say "there were no Christians until after the death of Christ", again you are correct according to the letter of the law and the spirit of the law is missing. You are legally correct in saying this, but Christ was from the beginning. Christ is all through scripture.There were no Christians until after the death of Christ. I am not going to create a palatable lie in order to convince some people to be Christians today. They either believe the Book or they don't.
In the first churches after Christ the Jews and Christians met together in the synagogues to worship God, seeing nothing wrong in this. Salvation was given from the beginning of time based on innocent blood, and it is carefully shown that it was a symbol of the blood of Christ with some of the same characteristics such as from animals without blemish. Men were given forgiveness of sin, based on this. Salvation was always given with faith the requirement. Often, in todays understanding of the Lord, this is not respected and Christ is preached as a new God rather than the Son that God had from the beginning.
Not recognizing this is a basis of the gentile/Jew relationship breakdown that is not of God.