What does Luke 2:50 mean?

Jesus has just explained to his flustered family that they should not have needed to "search" for Him. When He came up missing a day after the family left Jerusalem (Luke 2:41–45), they should have assumed that He would be in the temple (Luke 2:46–47). His mother was clearly upset about the situation (Luke 2:48), while Jesus responded that He would obviously have been in "[His] Father's house" (Luke 2:49). By saying this, Jesus alludes to His divine nature and His identity as the very Son of God (Luke 1:34–35; Matthew 1:18–21; John 1:34).

Hindsight is more powerful than we realize. Modern readers benefit from a perspective unavailable to Mary and Joseph: we can know in advance all that will happen, and all Jesus will do. That they don't understand the meaning of Jesus' comment is not worthy of condemnation. The same is true of the many times Jesus' disciples seem—again, in hindsight—to be slow to grasp concepts we now see as obvious (John 10:6; 12:16; Mark 6:52).

Whether or not Mary completely understands, she still displays a humble and open-minded approach. She once again (Luke 1:38; 2:19) is said to pay special attention, making a conscious effort to remember all that is happening (Luke 2:51).