Luke 1:1-4
Introduction
1 Many have undertaken to draw up an account of the things that have been fulfilled among us, 2 just as they were handed down to us by those who from the first were eyewitnesses and servants of the word. 3 Therefore, since I myself have carefully investigated everything from the beginning, it seemed good also to me to write an orderly account for you, most excellent Theophilus, 4 so that you may know the certainty of the things you have been taught.
St. Luke wrote a two volume work that includes the Gospel According to St. Luke and the Acts of the Apostles....
St. Luke immediately tells us many have undertaken to write about Jesus and the Good News...We don't know how many "many" means here, but we do know that others were writing and documenting things about our LORD...The oral stories of Jesus were now being written down by others, by "many"...
St. Luke tells us he has undertaken the responsibility to write the Gospel According to St. Luke...He would attempt to write the accounts of Jesus as they were handed down by the actual eyewitnesses...He knows St. Paul...In fact, it is St. Paul who tells us that Luke is a physician and dear friend in Colossians 4:14...St. Paul worked with St. Peter, the disciple of Jesus...In the Acts, St. Luke writes of many of the disciples and original eyewitnesses of Jesus...So we know St. Luke knew and had good access to the original eyewitnesses of Jesus...
St. Luke writings are addressed to Theophilus...Theophilus means friend of God...St. Luke may be writing this to an actual person named Theophilus or maybe writing it to us and any who are friends of God...Maybe he had the intuition to know it was being written to both...
The stories of Jesus would have been handed down orally...Jesus resurrection was still in the minds of all His followers...As I stated earlier, in St. Luke's second volume he writes about the Acts of the disciples, including St. Peter, St. John, St. Paul, St. Stephen among others...St. Luke would put these oral stories down in writing so they could be preserved and shared for years...
So as he worked with this group to write the story about our Messiah, he brings the eyewitnesses to us (in his writings) during Jesus' ministry and after His resurrection in the Acts...
In his final verse in his introduction, he wants us to be certain of the things we have been taught, about our Messiah...That he, St. Luke has examined the facts about Jesus and would write about those things...
This is the purpose he wrote this gospel so we would know by his words and his fact checking that Jesus lived, taught, healed, died for our sins, and was resurrected by God... And that his followers and disciples, at first struggled with the resurrection as man would, then believed in Him and praised God for sending Him...