The text of Mark 3:31-35 is:
31 Then Jesus’ mother and brothers came and stood outside. They sent someone in to summon Him, 32 and a crowd was sitting around
Him. “Look,” He was told, “Your mother and brothers are outside,
asking for You.”
33 But Jesus replied, “Who are My mother and My brothers?” 34 Looking at those seated in a circle around Him, He said, “Here are My
mother and My brothers! 35 For whoever does the will of God is My
brother and sister and mother.”
Some see in this Jesus' family trying to bask in Jesus' growing fame and adulation by claiming familial ties. However, this cannot be confirmed completely.
However, I think the primary lesson from Jesus, on this occasion, was the following:
- That Jesus' disciples were as precious to Him as his biological family.
- All Jesus' disciples share the privilege of being closely connected to Him as if they were biological family. The NT regularly speaks of Jesus as our "brother", Heb 2:11-13, 17, Ps 22:22, Isa 8:17, 18, Matt 12:48, 49, John 20:17, Rom 8:29
- biological family members could sometimes be a hindrance to spiritual progress. Thus, Jesus taught that our spiritual family must take precedence over our biological family, Luke 14:26, Matt 19:29, Mark 10:30
- the method by which a person/disciple is adopted into the family of Jesus and to be able to call Jesus "my brother", is to do "the will of God". Luke 8:21, Mark 13:35, Matt 12:50.
Having said that, Jesus did not ignore His biological family. On the cross, during his dying hours, He still thought of His mother and provided for her, John 19:26, 27.
Matthew Henry says this:
Mark 3:31-35 It is a great comfort to all true Christians, that they
are dearer to Christ than mother, brother, or sister as such, merely
as relations in the flesh would have been, even had they been holy.
Blessed be God, this great and gracious privilege is ours even now;
for though Christ's bodily presence cannot be enjoyed by us, his
spiritual presence is not denied us.