A very subtle form of opposition arose from Jesus' physical family members. It provided an opportunity for Jesus to explain true relationship to Messiah.
12:46-47 Jesus' brothers were evidently his physical brothers, the sons of Mary. Some Roman Catholics desiring to maintain their perpetual virginity of Mary doctrine have argued that they were Jesus' brothers but the sons of Joseph by a previous marriage.516If they were, the oldest of these brothers would have been the legal heir to David's throne.
12:48-50 Jesus' question did not depreciate His physical mother and brothers. His answer showed that He simply gave priority to His Father and doing His will. Spiritual relationship takes precedence over physical relationship (cf. 8:18-23). This underlines the importance of believing in Jesus and giving Him first place. Jesus' disciples become His true family.
These verses have strong Christological implications. They also reveal more about the spiritual family that was forming around Jesus. In spite of rising opposition, God's purposes through Messiah were advancing (cf. vv. 18, 20).