We don’t have much information about Jesus as a child. To be specific, we have one short story between the death of Herod the Great (Jesus aged 2-ish) and Jesus’ baptism at age 30-ish – the account of Jesus in the Temple as a 12-year old boy.
It is bracketed by two tantalising phrases:
And the child grew and became strong; he was filled with wisdom, and the grace of God was on him.
Luke 2:40 (NIV)
And Jesus grew in wisdom and stature, and in favour with God and man.
Luke 2:52 (NIV)
And this raises some interesting questions. How much did Jesus know about his mission? We know that Jesus wasn’t quite omniscient as a man (Matt 24:36) but certainly knew far more than other people. How much did he know as a child? And what does it mean for him to be God and human, when God is omniscient and humans aren’t?
We get some important insight into this in Philippians 2.
[Jesus], being in very nature God,
did not consider equality with God something to be used to his own advantage;
rather, he made himself nothing
by taking the very nature of a servant,
being made in human likeness.
And being found in appearance as a man,
he humbled himself
by becoming obedient to death –
even death on a cross!
Philippians 2:6-8 (NIV)
Jesus was in very nature God, but he emptied himself. The theological term for this is kenosis, which just means “emptying”. He emptied himself of all his power and wisdom and omnipresence and other divine attributes when he took the nature of a servant. When he does miracles, for example, he does them by the power of the Spirit working in him and following what he sees his Father doing (e.g. John 5:19).
So, back to Luke 2, and verse 40 is clearer in the original than in translation. Here it is with the verb tenses.
The child grew (imperfect active) and became strong (imperfect passive), being filled (present passive participle) with wisdom.
In other words, Jesus grows in size and strength, but is continually filled with wisdom (presumably by the Spirit) as his capacity increases.
Jesus is never less than full of wisdom because of the Holy Spirit, but a 2-year-old who is filled with wisdom is very different from a 30-year-old who is filled with wisdom because they have different capacities.
Therefore, when Jesus empties himself to become human, he empties himself all the way to the capacity of a baby. As he grows, the Holy Spirit keeps filling him with wisdom, presumably largely through the teaching of his parents and reading and hearing the Scriptures.