While he was still speaking to the crowds, his mother and his brothers were standing outside, wanting to speak to him.  Someone told him, "Look, your mother and your brothers are standing outside, wanting to speak to you."  But to the one who had told him this, Jesus replied, "Who is my mother, and who are my brothers?"  And pointing to his disciples, he 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."

In this moving episode Jesus ties together three other elements of his teaching into one and introduces a new teaching. 

The first two of the three teachings he ties together show how relationships in the kingdom exceed human bonds on earth, be they marital bonds or family bonds: "In the resurrection they neither marry nor are given in marriage, but are like angels in  heaven." (Matthew 22.30)  "Whoever loves father or mother more than me is not worthy of me; and however loves son or daughter more than me is not worthy of me." (Matthew 10.37)  The third of the three teachings has to do with the necessity of doing God's will to enter the kingdom: "Not everyone who says to me, 'Lord, Lord,' will enter the kingdom of heaven, but only the one who does the will of my Father in heaven." (Matthew 7.21)

The new teaching Christ introduces is the intimate familiarity he will have with us in his kingdom, calling us brother, sister and even mother.  The soul almost doesn't want to believe in that level of divine intimacy; it dare not hope for such a bond with its creator and redeemer.  But this is the level of intimacy awaiting those who do God's will, even unto being Christ's very own friends: "You are my friends if you do what I command you.  I no longer call you servants but friends." (John 15.14-15)