It's hard to translate literally what Jesus says about himself, and perhaps (as he will later) he chooses his words carefully. While most English translations like "in my Father's house" and some "about my Father's business," the Greek is a difficult expression -- en tois tou patros mou -- 'in those of my father' is a fair literal rendering but unsatisfying in English. Greek lacks any word for "house" or "business" but the weak noun "tois" implies content -- the things of my father, perhaps, and either sense, the temple or the affairs, works on a surface reading.
What is perhaps notable is that Jesus, at twelve, recognizes that God is up to stuff. God has concerns, places, people, arrangements. There are ways of spending time that do not align with the things of God, and there are ways of spending time that do. In his adult preaching, this idea will grow and flourish into the center of Jesus' teaching -- the kingdom of God, which again is a poor English rendering of something that Jesus makes immeasurably deep and significant. The kingship, the rule, the obedient community, the glorifying actions, the willing servants -- all this is incorporated in Jesus' teaching about the kingdom of God. At twelve, teetering on the edge of adulthood in Jewish society of the time, Jesus senses himself called to be in the things of his Father.
Without doubt there are tons of questions we'd like to ask. Had Mary and Joseph told Jesus the story of his remarkable conception? What were the questions and answers he bantered about with the Jewish teachers? Was this a singular incident, or typical of his childhood? This incident in Luke's narrative is the only detail we have from Jesus' childhood and youth. A couple centuries later, the Gnostics would make a growth industry out of fabricating spectacular stories of Jesus as a child -- clay sparrows brought miraculously to life, a playmate struck dead and then resurrected. These stories serve the Gnostics' agenda and have no discernible basis in fact, and they don't ring true to the sense of the canonical gospels. There's no call to take them seriously, especially when doing so compromises and contradicts what we know of Jesus from the earliest sources. But we feel the yearning to know more.
One more word of all those in this story. While Jesus speaks in less than clear terms about what he means by his Father's business / house, he is absolutely clear in another word he uses. "Dei" in Greek is a word for necessity -- English renders the phrase here "I must be" or "I need to be" and in Greek this is a strong imperative statement. Jesus considers this necessary. He has not willfully chosen an option, disregarding his parents' concerns. He is not acting on a whim. It is absolutely needful that he should be pursuing the things of his Father. A few years later he will state this more fully for his followers -- "Seek first the kingdom of God and his righteousness" (Matthew 6:33). At twelve, Jesus is following this command himself.
It is less than helpful to imagine Jesus in a superhero role here, omniscient at twelve years old, knowing all secrets and the like. We distance ourselves from him when we view him in this way. Luke and the other gospel writers are at pains to show Jesus in his full humanity, and that means that at twelve, he is a maturing child, beginning to grasp his identity as a man, sensing the beginnings of how God has wired him and what his life will be about. This story at its best pushes us to consider our own necessity, to consider what those things of God are that have been hardwired into our own awareness. What is it needful today for you to be doing? What is the business of your heavenly Father that you need to be concerned about today? None of us is capable of wrapping our arms and brains and hearts around the entire counsel of God, but he has given each of us a place, a corner of his kingdom, with which to concern ourselves. He has given each of us a voice, a role. Can you find yours? Without doubt, there will be others who share that area of interest, and part of the joy of being about your Father's business is the joy of harmonizing your voice with others who see things from a similar vantage point. This might be one reason why Jesus stayed in the temple after his extended family left for Nazareth -- he was immersed in joyful conversation about the things of God with others who shared his passion. None of us, not even Jesus, was intended to have these conversations and pursue this kingdom alone.
Yet Luke also tells us that Jesus knew the vision wasn't fulfilled (as Oswald Chambers writes in today's excellent meditation). He submitted to his parents and returned to Nazareth, and so the tantalizing glimpse draws to a close. We long to know the mundane details of Jesus at fifteen, at twenty, at twenty-five, but the next view we'll get is of the adult Jesus sensing that the time has come to begin his ministry, and the impetus for that will be his cousin John's voice ringing through the Jordan valley with a call to repentance.