You can choose your friends but you can’t choose your family - so the saying goes. I remember some teenage angst around that theme!
In Christian communities it is common for people to talk in terms of being a family of Christians. At baptisms, the newly baptised are welcomed ‘into the Lord’s family’. In some congregations it is normal for church members to refer to each other as ‘sister’ and ‘brother’. It reinforces the sense of common identity.
How does one get to be part of this Christian family?
St Paul, in his letters, consistently refered to his fellow believers as ‘brothers’, but he didn’t only address fellow Christians in that way. He called his fellow Jews brothers, whether or not they followed Jesus. He even used the term to address those members of the Jewish council who attacked him, attempted to kill him and then campaigned to have him executed. (See the opening sentences of Acts 23).
Paul used the word 'brothers' very broadly. Jesus, on the other hand, didn’t use the term very often outside his own immediate family. On one notable occasion, however, he was teaching in a house when he was told that his mother and brothers were outside, waiting to see him. Pointing at the disciples seated around him, Jesus said, "Here are my mother and my brothers! For whoever does the will of my Father in heaven is my brother and sister and mother.”
The assumption of the baptism service is that people become part of God’s family by being baptised. But that’s not what Jesus said. The assumption of many Christian communities is that we become part of God’s family by virtue of our shared belief in Jesus. He didn’t say that either. What Jesus said was, “Whoever does the will of my Father in heaven is my brother and sister and mother.” Membership of Jesus’ family comes from doing - not from rituals or beliefs, but from what we do. Anyone who does God’s will is in.
Jesus isn't asking us to talk like family, or to feel life family. Jesus wants us to be doing his family's business.