In Matthew, the angel appears to Joseph in a dream and tells him that Mary's child will save his people from their sins. In Luke, the angel tells Mary that her son will be great, he will be called the Son of the Most High and will rule on David's throne forever. A short time later Mary tells Elizabeth that all generations will consider her (Mary) blessed because of the child that will be born to her. If this were true, Mary and Joseph should have had the highest regard for their son. Instead, we read in Mark 3:20-21 that Jesus' family tried to take custody of him because they thought he had lost his mind. And later, in Mark 6:4-6 Jesus complained that he received no honor among his own relatives and his own household.How shall we answer this observation of the failure of Jesus' family to take His identity to heart? In this case, the answer is relatively simple. It is this: the records of the euphoric pre-birth statements made by the angel and Mary are separated in time from Mark 3:20-21 by approximately 30 years. Our author of this objection seems to think, in spite of the overwhelming evidence of the fickle nature of human beings, that something someone believed and thought 30 years in the past should remain the same in content after the passage of 30 years! His own writings suggest to me that he doesn't believe today what he once believed many years ago, so how is it that he thinks the people in the Bible should have a different nature than his own? Is it unreasonable to consider that the circumstances of Mary's experiences over 30 years would put in limbo some of the things she believed in the beginning? The same Bible that tells us that John the Baptizer announced Jesus by saying "Behold, the Lamb of God, Who takes away the sin of the world!" tells us that when John was tossed into convictional limbo by Herod's treatment of him (and God's willingness to allow that treatment), he sent disciples to Jesus to ask Him if He was the One they were to be looking for! Does this mean the Bible is contradictory, or that people are simply people -- whose convictional base changes over time and through difficult circumstances?
Actually, I would suspect the Bible more if it were sanitized of its record of human frailty! So, rather than this argument sustaining a notion of the untrustworthiness of the biblical record, it actually is an argument for believing it with greater conviction. The Bible claims to be the record of the Truth, not a sanitized record of what ought to have been true. King David was highly exalted by God to the position of King over God's Kingdom. He paid God back by committing adultery with Bathsheba! Does this mean the Bible is lying to us? Or does it simply mean that people are the liars, and the failures?
At the heart of the biblical message is this claim: all men are sinners and liars. The author of the complaint about Mary and the family of Jesus apparently doesn't take that message to heart at all!