The primary source of the appeal of Christianity was Jesus - His incarnation, His life, His crucifixion, and His resurrection.
The most that one of Jewish faith can do - and some have gladly done it - is to say that Jesus was the greatest in the long succession of Jewish prophets. None can acknowledge that Jesus was the Messiah without becoming a Christian.
John the Baptist, who we are told was related by blood to Jesus, was preaching the impending judgement of God, urging repentance and moral reform, and baptizing in the Jordan River those who responded.
However incompatible the spirit of Jesus and armed force may be, and however unpleasant it may be to acknowledge the fact, as a matter of plain history the latter has often made it possible for the former to survive.
It is not His teachings which make Jesus so remarkable, although these would be enough to give Him distinction. It is a combination of the teachings with the man Himself. The two cannot be separated.
As the centuries pass, the evidence is accumulating that, measured by His effect on history, Jesus is the most influential life ever lived on this planet.