Direct biblical statement
Mark 3:31–35
Those who do God’s will
31 And his mother and his brethren came; and standing without, sent unto him, calling him.
32 And the multitude sat about him; and they say to him: Behold thy mother and thy brethren without seek for thee.
33 And answering them, he said: Who is my mother and my brethren?
34 And looking round about on them who sat about him, he saith: Behold my mother and my brethren.
35 For whosoever shall do the will of God, he is my brother, and my sister, and mother.
Douay–Rheims · Challoner revision · Mark 3:31–35
Why this matters
Jesus’ mother and brothers arrive, and he speaks of those who do God’s will as his family. The text teaches spiritual kinship and does not directly assert a Marian doctrine.