Q. If Joseph was Jesus’ legitimate father, then Jesus was never a Son of God! He was but a wandering preacher, a man of human stock. How can you address this?
A. I fully understand your difficulty, because the idea that Jesus could not be the Son of God if he had a human biological father is deeply ingrained in Christian tradition. However, that belief is not actually in the New Testament. Please consider three things: (1) Paul never mentions anything about Jesus being born miraculously. If Paul believed that, it is very hard to understand why he never mentions it. Yet, Paul clearly believed that Jesus was Gods’ son. (2) The same is true for the Gospel of Mark. Again, the belief that Jesus was God’s son is, in this gospel, completely unconnected to any mention of a miraculous birth. (3) In the Gospel of John, Jesus is described as “him about whom Moses in the law and also the prophets wrote, Jesus son of Joseph from Nazareth” (John 1:45). John believes that Jesus is God’s son, in fact, a son equal to God himself; but John assumes that Jesus was born to a human father, just like all humans.
My point is that the New Testament shows that belief in Jesus as the Son of God does not depend on belief that he was born without a human biological father. So, although it is unusual in today’s Christianity, it seems perfectly acceptable to believe both in Jesus as God’s son and to assume (believe) that Joseph was his natural father.