What does Luke 2:40 mean?

Very little is told about Jesus' childhood, between His birth and the beginning of His public ministry. The few stories which are recorded are here in the Gospel of Luke. One is the encounter between an infant Jesus, Mary, Joseph, and the devout Simeon in the temple (Luke 2:25–32). Another, on the same day, involves the prophetess Anna (Luke 2:36–38). Another is an incident, when Jesus is twelve, where his family loses track of Him only to find Him in the temple (Luke 2:46–49).

This verse comes with tremendous implications. Jesus Christ is the Son of God—God incarnate—and divinity in human form (Hebrews 1:3; John 1:1, 14). However, His humanity is complete. Jesus' early life included almost everything universal to mankind while growing out of infancy, including physical and intellectual development. The only thing Jesus did not experience was sin (Hebrews 4:15; 1 Peter 2:22). After the incident at the temple, Luke will once again point out that Jesus' youth included growing, learning, and developing (Luke 2:52).

A common point of controversy about these verses is rooted in the claim that Jesus was "perfect," therefore He could not learn nor develop. This presumes that Jesus already knew everything, actively, and never gained information from anyone. It's helpful to remember that not all "mistakes" are "sins." A child who sincerely forgets the name of a carpentry tool, makes an arithmetic error, or trips while learning to walk is not committing sin. Nothing in Scripture suggests Jesus' divine nature disqualified Him from the human experiences of learning and development.