A picture of all four Gospel writers. Luke is the one on the far left signified by the symbol of the bull/calf he is "sitting on". This symbol is because Luke writes his Gospel with Jesus painted as the sacrfice and priest for all nations. By Peter Paul Rubens in 1614.

Authorship

The books of Luke and Acts are technically written by an anonymous author. No where in the text of Luke-Acts does the author explicitly identify himself. However, there are two kinds of evidence that can and do help us to know who the author of the books we call Luke and Acts was.

Internal Evidence

The author of Luke and Acts was a travel companion of Paul. This can be seen in the "we" passages that are scattered throughout the book of Acts (16:10-17; 20:5-21:18; 27:1-28:16). We also know that Luke was one of the travel companions of Paul and had a close relationship with him (Colossians 4:14).

External Evidence

The authorship of Luke and Acts being contributed to Luke, the travel companion of the Apostle Paul also comes from early reliable historical sources outside of the Bible itself. These include Eusebius, The Muratorian Canon (which is the earliest manuscript listing the books of the New Testament and many of the authors), Irenaeus, Clement of Alexandria, Tertullian, Origen, and the document known as the Anti-Marcionite Prologue.

In the history of the church Luke has been unanimously credited as the author of Luke and Acts until more liberal scholarship in the nineteenth century questioned his authorship. It is safe to say that Luke, travel companion of Paul, and first century Christian and missionary was the author of Luke and Acts.

Recipient(s)

Both Luke and Acts are written to an individual named Theophilus (Luke 1:3-4; Acts 1:1-2). Some scholars believe that Theophilus (whose name means "friend of God") is actually referring to a group of people. However, because Luke refers to him as "most excellent Theophilus (Luke 1:3-4) most scholars believe him to be a well-known Roman official who more than likely was financing the writing of Luke and Acts. (Paper was scarce in the first century and documents the size of Luke and Acts written by hand on parchment would have been particularly expensive, especially if more than one copy was created.) However, we also know from history that documents like this that were "commissioned" by a wealthy patron were often made for the express purpose of spreading them to larger audiences in multiple copies. It is extremely likely that this is exactly the case with both Luke and Acts. Therefore Luke writes specifically for Theophilus "so that [he] may know the certainty of the things [he has] been taught." (Luke 1:4), and more generally for the believers who would read his two-part work for centuries to come.

The recipients therefore for the books of Luke and Acts are: (1) Theophilus, (2) The early church (especially the Gentile believers), and (3) for all those who would choose to follow Jesus and seek to learn what it means to be the people of God who are living according to his will and acting as his agents and ambassadors in the world.

Dating

There are two theories in scholarship as to when the books of Luke and Acts were written. One is the early dating (60-63 AD) and the other a later dating (70-85 AD). The argument for each theory revolves primarily around one or two features of Luke-Acts: (1) the destruction of the Temple in Jerusalem, and (2) the seemingly abrupt ending of the book of Luke.

Arguments for the earlier dating of Luke-Acts (60-63 AD)

Proponents of an earlier dating for Luke-Acts point to the details concerning the destruction of the Temple (Luke 21:5-38) as a powerful and detailed prediction of the destruction of the Temple at Jerusalem in AD 70, and also see the seemingly abrupt ending of Acts as appropriate since that was the current situation when Luke was finished writing the book of Acts.

Arguments for the later dating of Luke-Acts (70-85 AD)

Proponents of an earlier dating for Luke-Acts point to the details concerning the destruction of the Temple (Luke 21:5-38) as a powerful and detailed emphasis placed by Luke on an even that had either just recently or in the last decade had transpired. Also, concerning the abrupt ending of the book of Acts simply state that Luke's intentions were simply to show that the gospel reached Rome and that historical details after that point were outside the scope of the purpose for Luke's writing.

While scholars do not really have a consensus concerning the exact dating of Luke-Acts, it seems most likely that the earlier dating is closer to the historical situation out of which Luke wrote both the books of Luke and Acts.