I have to agree with the she-elephant where she says “I doubt whether he or Mary or Joseph or any of his immediate disciples ever thought of themselves as anything but followers of Judaism.”
At that early date, the term “Christianity” didn’t even exist. It had not yet evolved into a separate religion from Judaism, so there was nothing to “convert” to. The immediate disciples of Jesus considered themselves Jewish, but with a twist – they considered Jesus the Jewish messiah. Other than that though, they continued practicing Jewish customs, observing Jewish holidays, and all the rest of it. They did not consider themselves a part of a separate religion. They were very different than Paul in that respect.
According to the Bible, did Mary convert to Christianity - ie follow the teachings of Jesus?
I assume you’re talking about Mary Magdalene. There’s so many Marys in the N.T. that it’s hard to know. After the resurrection accounts in the gospels, Mary Magdalene completely disappears from the story. She is never mentioned again in any of the epistles, Acts of the Apostles, or anywhere else. There are very late legendary accounts about her, but they are unreliable. Nobody knows what became of her.
If the Mary you are referring to is Mary the mother of Jesus, she is mentioned one time outside of the gospels, and that is in the book of Acts, where she is gathered with the others in the upper room to pray. After that, she too completely disappears from the record. As with Mary Magdalene, there are traditions about what became of her, but they date from centuries later and are therefore unreliable.
According to the Bible, did Joseph convert to Christianity – ie follow the teachings of Jesus?
The last time Joseph is mentioned in the Bible is when Jesus was twelve years old and his family couldn’t find him and thought he was lost. Of course they found him eventually in the temple. After that, Joseph is never mentioned again. Most scholars believe that he must have died sometime before Jesus began his ministry. At the wedding in Cana, Mary is mentioned, but Joseph is conspicuously absent. And during the crucifixion, Jesus commits the care of his mother into the hands of John. Had Joseph been alive at that time, there would have been no need for Jesus to do that.
According to the Bible, did Jesus's siblings convert to Christianity - ie follow the teachings of Jesus?
Yes, the siblings of Jesus, or at least some of them, did follow the teachings of Jesus. We know from the gospels that Jesus had four brothers, and several sisters. Of these, the only one we know much about is James, who became the leader of the original Jerusalem church, the hub of Christianity in the early years. The rest of the brothers were apparently traveling missionaries, much like Paul was. We know this from a passing comment about traveling missionaries that Paul himself made in I Corinthians 9:5: “Do we not have a right to take along a believing wife, even as the rest of the apostles and the brothers of the Lord and Cephas?” Whichever “brothers of the Lord” Paul is referring to here, it probably did NOT include James, since James was not a traveling missionary but was permanently stationed in Jerusalem. That means that Jesus’ other brothers must be the ones Paul had in mind.
Fun fact:
The siblings of Jesus were not the only ones related to him by blood who were involved the the faith. Numerous descendants of the family of Jesus had influential positions in the Christian church for over 100 after the death of Jesus, though we know little or nothing about most of them. James, as you know, was the first leader of the Jerusalem church. After he was killed, the next leader's name was Simeon. Simeon was the nephew of Joseph and Mary. Presumably he was chosen because he, like James, was a blood relative of Jesus. In the early-to-mid second century, the final Jewish leader of the Jerusalem church was chosen. His name was Judah Kyriakos. He was the great-grandson of Jude, one of the brothers of Jesus. He is the last known blood descendant of Jesus' family.
