Problem: Roman Catholicism teaches that Mary was a perpetual virgin, that is, that she never had sexual intercourse, even after Jesus was virgin born. Is it true that when the Bible refers to Jesus’ “brothers and sisters” (Matt. 13:56) it means cousins or close relatives?
Solution: It is true that the words for brother and sister can mean close relative. This must be determined by the context and from other Scriptures. And in the case of Jesus’ brothers and sisters, the context indicates they were his real half brothers and sisters.
First, nowhere does the Bible affirm the doctrine of Mary’s perpetual virginity. Like the Roman Catholic doctrine of Mary’s sinlessness (see comments on Luke 1:46), there is no statement anywhere in the Bible that supports this teaching.
Second, when “brothers and sisters” are used in connection with father or mother, then it does not mean cousins, but actual blood brothers and sisters (cf. Luke 14:26). Such is the case with Jesus’ brothers and sisters. Matthew 13:55 says, “Is not this the carpenter’s son? Is not His mother called Mary? And His brothers James, Joses, Simon, and Judas?” (cf. Mark 6:3)
Third, there are other references in the Bible to Jesus’ “brothers.” John informs us that “even His brothers did not believe in Him” (John 7:5). And Paul speaks of “James, the Lord’s brother” (Gal. 1:19). On another occasion Mark refers to “His [Jesus’] brothers and His mother” (Mark 3:31). John spoke of “His mother, His brothers, and His disciples” (John 2:12). Luke mentions “Mary the mother of Jesus, with His brothers” being in the Upper Room (Acts 1:14).
“And his sisters, are they not all with us? Whence then hath this man all these things? (Matt 13:56)”