I’m answering a question often asked of me by atheists – What would move a strong atheist to become a strong theist? In my case the answer was evidence for theism, specifically for Christian theism.

We started sharing the evidence that can lead an atheist to theism and Christianity several years ago (click here to read the first article in this series). We’ve most recently been looking at evidence for the reliability of the New Testament writings.

So far we’ve looked at –

We move now to the evidence for Luke’s authorship of the Book of Acts.

[Just a reminder that we’re only revealing the evidence available in the early part of 1971 during my investigation. A future series will look at evidence that has been discovered since that time.]

Here is a basic investigative process for determining ancient authorship:

  • Internal evidence – what we find in the letter itself .. claim of authorship, historical information, geographical information, biographical information.
  • Language and style – comparing writing style of other letters believed to have been written by same author (e.g. vocabulary, sentence structure, grammar, idioms).
  • Content – comparing the content with other letters believed to have been written by same author (e.g. theology, historical data).
  • External evidence – ancient writers supporting claim of authorship, ancient writers quoting from writings in question.

Book of Acts

“The former account I made, O Theophilus, of all that Jesus began both to do and teach, until the day in which He was taken up, after He through the Holy Spirit had given commandments to the apostles whom He had chosen, to whom He also presented Himself alive after His suffering by many infallible proofs, being seen by them during forty days and speaking of the things pertaining to the kingdom of God.”

Acts 1:1-3

Internal Evidence

The author of Acts wrote about a “former account” (πρῶτον λόγον – first message, discourse) that he made to a man named ‘Theophilus’ ((Θεόφιλος – friend of God). That connects internally to the Gospel of Luke –

“Inasmuch as many have taken in hand to set in order a narrative of those things which have been fulfilled among us, just as those who from the beginning were eyewitnesses and ministers of the word delivered them to us, it seemed good to me also, having had perfect understanding of all things from the very first, to write to you an orderly account, most excellent Theophilus, that you may know the certainty of those things in which you were instructed.”

Luke 1:1-4

It appears that the person who authored the Gospel of Luke also authored the Book of Acts. Luke and Acts are both lengthy writings and may account for why the author wrote them as separate documents. The maximum length of an ancient Greek literary scroll was about 35 feet, so writers would often separate lengthy works into two or more scrolls – like volumes of the same work. That may be why the Gospel of Luke and Acts are presented as two volumes of writing to the same individual.

The author of the Gospel of Luke and the Book of Acts did not identify himself. However, the Apostle Paul mentioned a physician named Luke in his letter to the Colossians (4:14). Paul called Luke a ‘fellow laborer’ in his letter to Philemon (1:24). We know internally that Luke was connected to the apostle Paul, but is there any other internal evidence that Luke was the author of the Gospel of Luke and Acts?

The author of both letters stated the purpose was to present evidence about the life and ministry of Jesus Christ to a man named Theophilus. Both letters were written in refined Koine Greek. The author wrote in the Gospel of Luke that his purpose was to write a ‘narrative’ (διήγησιν – full account) of “those things which have been fulfilled among us.” He wrote that the Gospel narrative would be ‘orderly’ (καθεξῆς – orderly sequence, successfully). The author of Acts wrote that Jesus presented Himself alive after His suffering by ‘many infallible proofs’ (πολύς τεκμήριον – many certain signs, many irrefutable proofs).

From the brief introduction in both writings, we find that the author’s intention was the same – to present strong evidence for the truth claims concerning Jesus Christ’s life, ministry, death and resurrection. This presentation of evidence followed what the author described as an ‘orderly sequence’ of events. That may have demonstrated the way a physician, like Luke, would have considered information – presenting evidence in an orderly way.

The author described an investigative process of being certain about the evidence:

Gospel of Luke – ” just as those who from the beginning were eyewitnesses and ministers of the word delivered them to us”

Acts – “after He through the Holy Spirit had given commandments to the apostles whom He had chosen, to whom He also presented Himself alive after His suffering by many infallible proofs, being seen by them during forty days and speaking of the things pertaining to the kingdom of God.”

The author of Luke interviewed eyewitnesses of what happened in the life and ministry of Jesus Christ. The author of Acts also interviewed eyewitnesses of what happened in the early days, weeks, months and years of the Church that Jesus was building.

Comparing Acts to Apostolic Letters

Another internal evidence is comparing the events in Acts to those written by other writers in the apostolic letters. Acts is primarily chronological. It begins with the last words of Jesus to His apostles and His ascension to Heaven and ends with the Apostle Paul under house arrest in Rome. That covers a period of almost 30 years (33 – 60AD).

The early chapters of Acts focus on the life and ministry of Peter, James, John and other apostles and those who heard their message and trusted in Jesus Christ for salvation – primarily in Jerusalem and Judea. Though the letters of Peter, John and James did not detail their ministry travels, they did share their teaching. It is that teaching that can be compared to what Acts details as the apostles’ teaching in the early years of the Church. That comparison finds Acts in line with the teaching of the apostles in their letters.

Here are some examples for the Apostle Peter –

Acts and 1 Peter

“And we are His witnesses to these things, and so also is the Holy Spirit whom God has given to those who obey Him.” Acts 5:32

“To them it was revealed that, not to themselves, but to us they were ministering the things which now have been reported to you through those who have preached the gospel to you by the Holy Spirit sent from heaven—things which angels desire to look into.” 1 Peter 1:12

“Then Peter opened his mouth and said: ‘In truth I perceive that God shows no partiality.” Acts 10:34

“And if you call on the Father, who without partiality judges according to each one’s work, conduct yourselves throughout the time of your [a]stay here in fear.” 1 Peter 1:17

“This is the ‘stone which was rejected by you builders, which has become the chief cornerstone.” Acts 4:11

“Therefore, to you who believe, He is precious; but to those who are disobedient, ‘The stone which the builders rejected Has become the chief cornerstone.” 1 Peter 2:7

The author of Acts spent the majority of his writing on the life and ministry of the Apostle Paul. Paul often mentioned details of his missionary travels in his letters, so we can compare what he wrote with what the author of Acts wrote about Paul’s missionary travels. That comparison finds Acts in line with the details in Paul’s letters.

Here are some examples for the Apostle Paul –

Acts and Paul’s Letters

  • Acts 9, 22 and 26 claim that Paul was a Jew from Tarsus who persecuted the Church and was saved near Damascus through the personal intervention of Jesus Christ. Paul wrote in 1 Corinthians 15 and Galatians 1 that he persecuted “the church of God.” He wrote in Philippians 3 that he persecuted “the church.”
  • Acts 7 claims that Paul (Saul) was present at the stoning of Stephen, which led to Paul’s persecution of followers of Christ (Acts 8). Thought Paul didn’t mention Stephen by name in his letters, he did write about persecuting followers of Christ (see above).
  • Acts 9, 23 and 26 claimed that Paul saw a vision of the Lord as a bright light and heard his voice. Paul wrote in
  • Acts claims that disciples let Paul down a wall in Damascus to escape those who plotted his death. Paul wrote in 2 Corinthians 11 that he was let down in a basket to escape arrest in Damascus.
  • Acts referred to Paul as an apostle in Acts 14. Paul referred to himself as an apostle in most of his letters.
  • Acts referred to Paul as being a pharisee in Acts 23. Paul referred to himself as a former pharisee in Philippians 3.
  • Acts included information about Paul going first to Jews, then turning to Gentiles in cities he visited. Paul listed that order of Jew first, then Gentile, in Romans 1, 1 Corinthians 1 and 12, and Galatians 3.
  • Acts mentions several people who partnered with Paul for his missionary journeys, including Barnabas, Silas, John Mark, Silas (Silvanus) and Timothy (Acts 11, 12, 13, 14, 15, 16, 17, 18, 19, 20). Paul mentioned Barnabas in 1 Corinthians 9, Galatians 2, and Colossians 4. He mentioned John Mark in Colossians 4, 2 Timothy 4 and Philemon 1. Paul mentioned Silas (Silvanus) in 2 Corinthians 1, 1 Thessalonians 1, and 2 Thessalonians 1. He mentioned Timothy in Romans 16, 1 Corinthians 4 and 16, 2 Corinthians 1, Philippians 1 and 2, Colossians 1, 1 Thessalonians 1 and 3, 2 Thessalonians 1, 1 Timothy 1 and 6, 2 Timothy 1, and Philemon 1. Timothy is also mentioned in Hebrews 13.
  • Acts claims Paul journeyed to many countries, regions, cities and towns to preach the Gospel including Antioch (Acts 11, 13, 14, 15, 18), Athens (Acts 17 and 18), Cilicia (Acts 15, 21, 22, 23, 27), Corinth (Acts 18, 19), Crete (Acts 27), Ephesus (Acts 18, 19, 20), Galatia (Acts 16, 18), Jerusalem (Acts 9, 12, 15, 21), Macedonia (Acts 16, 19, 20), Miletus (Acts 20), Philippi (Acts 16, 20), Rome (Acts 18, 19, 28), Syria (Acts 15, 18, 20, 21), Thessalonica (Acts 17), Troas (Acts 16, 20). Paul mentioned his trips to various cities and towns in his letters including Antioch (Galatians 2, 2 Timothy 3), Athens (1 Thessalonians 3), Cilicia (Galatians 1), Corinth (1 Corinthians 1, 2 Corinthians 1, 6, 7, 2 Timothy 4), Crete (Titus 1), Ephesus (1 Corinthians 15, 16, Ephesians 1, 1 Timothy 1, 2 Timothy 1, 4), Galatia (1 Corinthians 16, Galatians 1, 3, 2 Timothy 4), Jerusalem (Romans 15, 1 Corinthians 16, Galatians 1, 2, 4), Macedonia (Romans 15, 1 Corinthians 16, 2 Corinthians 1, 2, 7, 8, 9, 11, Philippians 4, 1 Thessalonians 1, 4, 1 Timothy 1), Miletus (2 Timothy 4), Philippi (Philippians 1, 4, 1 Thessalonians 2), Rome (Romans 1, 2 Timothy 1), Syria (Galatians 1), Thessalonica (Philippians 4, 2 Timothy 4), and Troas (2 Corinthians 2, 2 Timothy 4).

The author of Acts began referring to ‘we’ and ‘us’ in Acts 16 –

“Now when they had gone through Phrygia and the region of Galatia, they were forbidden by the Holy Spirit to preach the word in Asia. After they had come to Mysia, they tried to go into Bithynia, but the Spirit did not permit them. So passing by Mysia, they came down to Troas. And a vision appeared to Paul in the night. A man of Macedonia stood and pleaded with him, saying, ‘Come over to Macedonia and help us.’ Now after he had seen the vision, immediately we sought to go to Macedonia, concluding that the Lord had called us to preach the gospel to them.”

Acts 16:6-10

The author of Acts used the ‘we’ and ‘us’ references in several sections of Acts. It may be that he used them as a testimony to his personal relationship with Paul and being an eyewitness to what God did through Paul’s preaching.

Here are several examples:

  • “Now it happened, as we went to prayer …” (Acts 16:16)
  • “This girl followed Paul and us …” (Acts 16:17)
  • “These men, going ahead, waited for us at Troas. But we sailed away from Philippi .. where we stayed seven days.” (Acts 20:5-6)
  • “Now it came to pass, that when we had departed .. finding a ship sailing over to Phoenicia, we went aboard and set sail. When we had sighted Cyprus, we passed it on the left .. finding disciples, we stayed there seven days .. when we had come to the end of those days, we departed .. we knelt down on the shore and prayed. When we had taken our leave of one another, we boarded the ship .. when we had finished our voyage from Tyre, we came to Ptolemais .. we who were Paul’s companions departed and came to Caesarea .. we stayed many days .. when we heard these things, both we and those from that place pleaded with him not to go up to Jerusalem .. we ceased, saying .. we packed and went up to Jerusalem. Also some of the disciples from Caesarea went with us .. And when we had come to Jerusalem, the brethren received us gladly …” (Acts 21:1-19)
  • “And when it was decided that we should sail to Italy .. we put to sea .. we landed at Sidon .. When we put to sea from there, we sailed under the shelter of Cyrus .. And when we had sailed over the sea .. we came to Myra, a city of Lycia .. he put us on board .. When we had sailed slowly man days .. we sailed under the shelter of Crete .. we came to a place called Fair Havens .. when the ship was caught, and could not head into the wind, we let her drive .. we secured the skiff with difficulty .. because we were exceedingly tempest-tossed .. we threw the ship’s tackle overboard with our own hands .. no small tempest beat on us, all hope that we would be saved was finally given up .. fearing lest we should run aground .. (Acts 27:1-38)
  • “And the natives showed us unusual kindness; for they kindled a fire and made us all welcome .. They also honored us in many ways; and when we departed, they provided such things as were necessary .. After three months we sailed in an Alexandrian ship .. And landing at Syracuse, we stayed three days. From there we circled round and reached Rhegium. And after one day the south wind blew; and the next day we came to Puteoli, where we found brethren .. And so we went toward Rome. And from there, when the brethren heard about us, they came to meet us .. when we came to Rome …” (Acts 28:1-16)

Next Time

We will look at external evidences for Luke being the author of Acts in the next part of our special series, Convince Me There’s A God: The New Testament.

Scripture taken from the New King James Version®. Copyright © 1982 by Thomas Nelson. Used by permission. All rights reserved.