Suppose someone wrote a book in 1980 describing your hometown as it was that year. In the book, the author correctly describes: your town's politicians, its unique laws and penal codes, the local industry, local weather patterns, local slang, the town's roads and geography, its unusual topography, local houses of worship, area hotels, town statues and scriptures, the depth of the water in the town harbor, and numerous other unique details about your town that year. Question: If the author claimed he had visited your town that year - or said he had gotten good information from people who had been there - would you think he was telling the truth? Of course, because he provides details that only an eyewitness could provide. That's the type of testimony we have throughout much of the New Testament.
Luke includes the most eyewitness details. (while Luke may not have been an eyewitness to the Resurrection itself, he certainly was an eyewitness to many New Testament events.) In the second half of Acts, for example, Luke displays an incredible array of knowledge of local places, names, environmental conditions, customs, and circumstances that befit only an eyewitness contemporary of the time and events.
Classical scholar and historian Colin Hemer chronicles Luke's accuracy in the book of Acts verse by verse. With painstaking detail, Hemer identifies 84 facts in the last 16 chapters of Acts that have been confirmed by historical and archaeological research. As you read the following list, keep in mind that Luke did not have access to modern-day maps or nautical charts. Luke accurately records:
(for the sake of brevity, it's in spoiler)
Is there any doubt that Luke was an eyewitness to these events or at least had access to reliable eyewitness testamony? What more could he have to prove his authenticity as a historian? Indeed, Luke's accuracy in Acts is truly amazing.
Now, here's where skeptics get very uncomfortable. Luke reports a total of 35 miracles in the same book in which he records all 84 of these historically confirmed details. Several miracles of Paul are recorded in the second half of Acts. For Example, Luke records that Paul: temporarily blinded a sorcerer (13:11); cured a man who was crippled from birth (14:8); exorcised an evil spirit from a possessed girl (16:18); "performed many miracles" that convinced many in the city of Ephesus to turn from sorcery to Jesus (19:11-20); healed Publius's father of dysentary, and healed numerous others who were sick on Malta (28:8-9). All of these miracles are included in the same historical narrative that has been confirmed as authentic on 84 points. And the miracle accounts show no signs of embellishment or extravagance - they are all told with the same level-headed efficiency as the rest of the historical narrative.
Now, why would Luke be so accurate with trivial details like wind directions, water depths, and peculiar town names, but not be accurate when it comes to important events like miracles? In light of the fact that Luke has proven accurate with so many trivial details, it is nothing but pure anti-supernatural bias to say he's not telling the truth about the miracles he records. So it makes much more sense to believe Luke's miracle accounts than to discount them. In other words, Luke's credentials as a historian have been proven on so many points that it takes more faith not to believe his miracle accounts than to believe them.
The Gospel of Luke
What about that Gospel of Luke? First, we need to recognize that Acts and the Gospel of Luke are closely related books. How do we know? First, both documents contain the same Greek vocabulary and literary style. But more important, Luke addresses both documents to "most excellent Theophilus." He was probably some kind of Roman official because "most excellent" is the same title Paul used to address the Roman governors Felix and Festus.
Regardless of the true identity of Theophilus, the main point is that Luke reveals that Acts is a continuation of his Gospel. His opening says, "in my former book, Theophilus, I wrote about all that Jesus began to do and teach until the day he was taken up into heaven..." (Acts 1:1). Luke uses the remainder of Acts to tell Theophilus what happened after Christ's ascension. And as we have seen, he did so with amazing precision.
Should we expect the same degree of accuracy from Luke's Gospel? Why not? In fact, Luke says as much when he writes, "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" (Luke 1:3). Judging from his meticulous work in Acts, Luke certainly is a careful historian who should be trusted. A historian who has been found trustworthy where he or she can be tested should be given the benefit of the doubt in cases where no tests are available. Since Luke has been tested on 84 points and has earned a perfect score, there's every reason to believe his Gospel is "gospel" as well.
But we don't have to rely solely on his work in Acts to confirm Luke's Gospel. There are several details in Luke's Gospel that have been verified independently. For example, Luke names eleven historically confirmed leaders in the first three chapters of his Gospel alone (twelve if you include Jesus). These include Herod the Great, (1:5), Caesar Augustus (2:1), and Quirinius (2:2). He then writes this at the beginning of chapter 3:
Does this sound like Luke is making up a story? Of course not. If he were, there would be no way he would put historical crosshairs on the events he's describing by naming these prominent leaders and their dates. A writer who thus relates his story to the wider context of world history is courting trouble if he is not careful; he affords his critical readers so many opportunities for testing his accuracy. Luke takes this risk, and stands the test admirably. Indeed, all eleven of the historical figures Luke names in the first three chapters of his Gospel - including John the Baptist - have been confirmed by non-Christian writers and/or archaeology. For example, John the Baptist is mentioned by Josephus (Antiquities 18:5.2), and an inscription dating from A.D. 14 to 29 bears the name of Lysanias.
Another historically accurate detail can be found in Luke 22:44. That's where Luke records that Jesus was in agony and sweat drops of blood the night before his crucifixion. Apparently, Jesus was experiencing a rare stress-induced condition we know today as hematohidrosis. That's when tiny blood vessels rupture due to extreme stress, thus allowing blood to mix with sweat. Since Luke probably didn't know of this medical condition 2,000 years ago, he could not have recorded it unless he had access to someone who saw it (Which btw, is incredible evidence suggesting Christ's foreknowledge of his arrest and crucifixion; otherwise why that level of stress? But that's a different topic...).
The bottom line is that Luke can be trusted. Since Luke can be affirmed independently on so many testable points, there's every reason to believe he's telling the truth elsewhere.
Now here's the crucial point: Since Luke is telling the truth, then so are Mark and Matthew because their Gospels tell the same basic story. This is devastating to skeptics, but the logic is inescapable. You need a lot of faith to ignore it.