Luke wrote his Gospel to Theophilus for a very specific purpose:
Luk 1:3 It seemed good to me also, having had perfect understanding of all things from the very first, to write unto thee in order, most excellent Theophilus,
4 That thou mightest know the certainty of those things, wherein thou hast been instructed.
In Acts 1, Luke informs Theophilus what his Gospel comprised:
Act 1:1 The former treatise have I made, O Theophilus, of all that Jesus began both to do and teach,
By correlating these two statements, we learn that the Gospel of Luke was written to give Theophilus certainty about what he had been instructed about all that Jesus began both to do and to teach.
Applying this understanding to what we find in the Gospel of Luke reveals a striking truth when we examine it for information about what Jesus began to do and teach—Luke 2:41-52 is the first information about what Jesus did and taught! Based on this fact, we understand that the narrative of what Jesus did and said when He was a twelve-year old boy in the temple is foundational for our having the certainty that God wants us to have about all of Jesus’ acts and sayings about which we have been taught!