Mark in his Gospel puts a lot of emphasis on “the Twelve”. The idea that there were 12 “apostles” is so deeply embedded in our church culture that we never think about it. There was Jesus, and the twelve, and then the rest. That’s pretty simple.
Except Paul was a bit of an anomaly, as he notes himself. And then there was Judas, who wrote himself out of the story but got replaced, in some accounts, so we still had the nice round dozen.
In fact each Gospel has widely varying accounts of Jesus’s close companions. They don’t even agree on the names beyond the first few. They are highly ambiguous about the role of women, but from what is mentioned it’s clear they were very important – but in that society they struggled with the idea of including women in the core team (has that changed?).
If we want to take the historian’s perspective we would easily conclude there were a wide range of people around Jesus, some traveling with him pretty much continuously (Peter, James and John), some definitely staying home but very close to him (Mary, Martha, Lazarus), some who were at his crucifixion (three Marys by some accounts). The neat dozen provides a neat link to the 12 tribes of Israel (which were also semi-mythical), and all that implied in the history of the chosen people, but it’s not a census count of who was where when.
But we aren’t really looking to the gospels for history lessons. We are looking for lessons in faith.
In matters of faith, simple suppositions can also be misleading. Jesus, and the prophets before him, right back to Moses, spent a lot of time correcting such presuppositions – or at least trying to. Today is a classic case (Mk 9:38-48). Mark doesn’t reference the Twelve in this account, and unusually has John play the bad guy rather than Peter. Regardless, however the “in-group” was defined by John (“one of us”), the previous story is explicitly directed at the Twelve, so Mark at least sets that context. Of course Moses had a different in-group who thought they were the bee’s knees (Nm 11:25-29). In that case there were 70 of them, which seems rather a lot, but it’s also a very important number, for people who think numbers are important. But both Moses and Jesus are absolutely clear that God has zero interest in any ideas about who is in and who is out, who is one of us and who is not.
Mark doesn’t just leave it at that. He continues with perhaps the strongest condemnation of bad behavior that we get from Jesus outside of his tirades against the Pharisees (who were by self definition the ultimate in-group). If any part of our body causes sin then we’d be better off without it (and this was in the days before surgery, so removing body parts was the ultimate horror). This follows the warning about mental sin (assuming that we’re in and others are out).
Are we ready to cut out whatever may cause us to sin, in mind or body?