First, however, we need to define what a Christian is before discussing Mary and Joseph. According to the Bible, a converted person is someone who has God's Holy Spirit dwelling within them (Romans 8:14 - 16, 2Corinthians 1:22, Acts 2:38, Ephesians 1:13 - 14). This spirit, which is not a person (e.g. Trinity), is the power God grants repentant humans to understand His truth and build righteous character.
Luke's gospel records three major events in Jesus' early life where Mary and Joseph were unable to grasp the basic meaning of events involving their miraculous Son.
The first event we will review is when angels, upon Jesus' birth, joyously announce his arrival to shepherds outside Bethlehem (Luke 2:8 - 14). After listening to what is proclaimed the shepherds seek out and find the Christ child. Once found, they reveal to his human parents that their child is the long awaited Savior of mankind (verses 11, 17).
Though the shepherds leave Bethlehem glorifying and praising God (Luke 2:20), Luke records no response from Joseph and states Mary, "stored up [kept to herself] all these sayings, pondering them . . ." (verse 19, HBFV throughout). Although their muted response is a bit odd, it makes sense if they simply did not understand the rich meaning of the momentous event (unlike countless angels who did) that occurred right in front of them!
Forty days after Jesus' birth both Mary and Joseph journey to Jerusalem to present their Son at the temple (Luke 2:22 - 38). After a priest named Simeon blesses the child, he reveals profound prophecies regarding the baby’s identity, his upcoming mission, and even the manifold effects of his ministry (verses 29 - 32, 34 - 35).
Mary and Joseph, however, are baffled when they hear Simeon's words (Luke 2:33). Their uncertainty on how to respond is contrasted with the response from a righteous widow named Anna. After also being privileged to see the newborn Savior at the temple, she rejoices over his birth. Her joy, and understanding of who Jesus was, leads her to spread the news throughout Jerusalem that the promised Redeemer has come into the world (verses 36 - 38)!
Doing his Father's work
Our last example, which is perhaps the strongest, that Mary and Joseph were not Christians (converted, saved) during Jesus' early life comes when he is twelve years old (Luke 2:41 - 50). The couple assumes, after leaving Jerusalem at the end of Passover, that Jesus also left the city with relatives. After they discover he is not with relatives they hurry back to the city. After three days of frantic and worrisome searching, they find their Son at the temple.
Mary, no doubt unhappy at her firstborn's behavior, chastises him by stating, "Son, why have You dealt with us in this manner? Look, Your father and I have been very distressed while searching for You" (Luke 2:48).
Jesus' respectful and corrective response to his parent's complaint is, "Why is it that you were looking for Me? Don't you realize that I must be about My Father's (God's, not Joseph's) business?" (Luke 2:49).
Scripture, after Jesus responds to his parents, states, "But they (Mary and Joseph) DID NOT UNDERSTAND the words that He spoke to them" (Luke 2:50). This and their previous lack of grasping a basic understanding of Christ’s identity and his purpose can only reasonably be explained if they were not Christians (did not have God's spirit).
Why did God use them?
Why did God choose to use Mary and Joseph even though they did not have his Spirit? It was because they obeyed his Old Testament laws, to the best of their abilities, and were considered righteous by him!
The Bible states Joseph was a "righteous man" when he wanted to initially divorce Mary privately (Matthew 1:19). As a couple, they obeyed God's law by having Christ circumcised on the eighth day (Leviticus 12:3, Luke 2:21).
Additionally, Jesus' human parents obediently presented him at the temple forty days after his birth (Leviticus 12:6, 8, Luke 2:22 - 24). They also kept God's commanded Feast days, which included the Passover (Deuteronomy 16:16 - 17, Luke 2:41).
Did they ever receive it?
Mary would not be given God's spirit until she and many others (including the apostles) received it and became Christians on Pentecost in 30 A.D. (Acts 1:14, 2:1 - 4). She will be in the first resurrection of the dead. No record exists, however, of Joseph receiving the Holy Spirit before his death.