Was the Writer of Luke the Same Who Wrote Acts?
It is evident that the author of Luke’s Gospel and the Book of Acts were the same. Luke and Acts were both addressed to one Theophilus with reference to the first made in the second: (Luke 1:1-4 and Acts 1:1-4, respectively). The events in Acts are a natural continuation and dovetail perfectly to the events written in Luke.
1 Forasmuch as many have taken in hand to set forth in order a declaration of those things which are most surely believed among us,
2 Even as they delivered them unto us, which from the beginning were eyewitnesses, and ministers of the word;
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. - Luke 1:1-4
1 The former treatise have I made, O Theophilus, of all that Jesus began both to do and teach,
2 Until the day in which he was taken up, after that he through the Holy Ghost had given commandments unto the apostles whom he had chosen:
3 To whom also he shewed himself alive after his passion by many infallible proofs, being seen of them forty days, and speaking of the things pertaining to the kingdom of God:
4 And, being assembled together with them, commanded them that they should not depart from Jerusalem, but wait for the promise of the Father, which, saith he, ye have heard of me. - Acts 1:1-4
What information can be known from the introductions?
- A number of partial and or disordered accounts of the facts of the life of Christ were extant at the time.
- These facts were well known to the Christian world of the day.
- The writer stated that his purpose was to put the events of the life of Christ in an accurate and logical order.
- His record goes back to and includes insights that would be known to apostles, eyewitnesses and possibly even relatives of Jesus.
- The author considered himself at least as well informed at the others and as capable of writing an account on his own responsibility (“it seemed good to me also”).
- He cites his sources as ‘eyewitnesses’ and ministers of the word who were able to account for things ‘from the beginning.’ This is a reference to the beginning of the information he sets forth to record before the birth of Christ.
He was a contemporary of the disciples and early church leaders.
Authorship and Occupation
The author was a participant in many of the events he writes about and fellow traveler with Paul proven by the “we” and "us" words he uses; The book of Acts goes on for 16 chapters before the “we” is introduced in Acts 16:10-12 (In one manuscript it appears as early as chapter 10). His occupation as a physician is noted in Colossians 4:14; “Luke, the beloved doctor, sends his greetings, and so does Demas.”
10. And after he had seen the vision, immediately we endeavoured to go into Macedonia, assuredly gathering that the Lord had called us for to preach the gospel unto them.
11. Therefore loosing from Troas, we came with a straight course to Samothracia, and the next day to Neapolis;
12. And from thence to Philippi, which is the chief city of that part of Macedonia, and a colony: and we were in that city abiding certain days. -- Acts 16:10-12
This establishes Luke as a traveling companion with Paul on his second missionary journey. He accompanied Paul to Philippi, but did not share his imprisonment there. After Paul’s release Luke remained at Philippi. On Paul's third visit to Philippi (20:5, 6) probably seven or eight years later, he meets with Luke and again they travel on together. From this time Luke was Paul's constant companion during his journey to Jerusalem (20:6-21:18).
The ‘we’ references eliminate Timothy and all of those mentioned in Acts 20:5 as writers because ‘we’ didn’t accompany these on their trip (Demos fell away from the faith and abandoned Paul so he’s not considered as the writer either). They all waited for “us” at Troas. Luke was a physician according to Paul and he was a man who could write well and was very observant as can be surmised from the best account we have of ancient shipping (Acts 27).
There is external evidence as well. The Gospel was used by Justin Martyr (second century), Tatian, Marcion and Tertullian who quoted or alluded to the Gospel in excess of five hundred times.
Luke was written after the death of Christ and before Acts was written. Since Acts ends abruptly with Paul’s confinement in Rome with no mention of Paul’s later travel to Spain or his execution which occurred under Nero about 67 AD. Some scholars fix the date of the writing of Luke around 60 AD or less than thirty years from Christ.
There is plenty of evidence I have not covered here but suffice it to say all the best evidence of the Gospel points to Dr. Luke being the author, contemporary with the Apostles.
 New Testament Survey Merril C. Tenney P. 173, 179.
Photograph/ last supper statues in Rhyolite, CA by R. Hoeppner