>>508742966Scholars and historians determine authorship with all ancient documents based on internal evidence and external attestation. The notion that a companion of Paul named Luke wrote the Gospel of Luke emerged 100 years after the text was written. The earliest external attestation comes from a source called the Muratorian Canon.
Most scholars believe it dates to the late part of the 2nd century. As J. Fitzmyer notes in his commentary on the Gospel of Luke, “the first reference to the tradition can be found in the Muratorian Canon, which has usually been assigned a date ca. 170-180. C.E.”
Lines 2-8 of the Muratorian Canon read: “The third book of the Gospel is that according to Luke. Luke, the well-known physician, after the ascension of Christ, when Paul had taken with him as one zealous for the law, composed it in his name, according to [the general] belief.”
Soon thereafter, bishop Irenaeus (c. 185 C.E.) claims in his work Against the Hearesis that Luke, “the companion of Paul, has compiled the Gospel preached by that one in a book (3.1.1.)”.
It is important to note we have quotations from the Gospel of Luke from earlier Church authors such as Ignatius of Antioch and Justin Martyr. However, they never name their source. E. P. Sanders remarks in The Historical Figure of Jesus: “The Gospels as we have them were quoted in the first half of the second century, but always anonymously. Names suddenly appear about the year 180.”
Consequently, the first external attestation for the authorship of the Gospel of Luke came a century after it was originally written. It is difficult to use this as accurate historical information. Therefore, most critical scholars reject the traditional theory.