Short answer: the most likely author is Luke — the same Luke who wrote the Gospel of Luke and the Acts of the Apostles. Evangelical Christians typically affirm Luke as the human author (under the inspiration of the Holy Spirit), a well-educated physician and companion of Paul, who carefully investigated eyewitness testimony to present an orderly, historically reliable account.

Why Luke is identified as the author
– Internal evidence: Luke’s Gospel opens with a prologue that says the writer carefully investigated the events and compiled an orderly account for “Theophilus” (Luke 1:1–4). The stylistic and linguistic continuity between Luke and Acts makes it clear they are a two-volume work by the same author.
– External evidence: Early church tradition (Irenaeus, Tertullian and others) attributes both works to Luke, the companion of Paul.
– New Testament corroboration: Paul refers to “Luke, the beloved physician” (Colossians 4:14), and the narrative in Acts contains several “we” sections that indicate the author traveled with Paul — consistent with Luke as a companion.

Who Luke likely was (evangelical perspective)
– A Gentile by background is often assumed (classical Christian tradition and internal clues), though not stated explicitly in Scripture.
– A physician (iatros) — suggesting medical training, attention to detail and technical vocabulary in places.
– Educated in Greek language and historiographical practices, which explains his polished Greek and orderly approach.
– Not an eyewitness of Jesus’ ministry in the sense of walking with Jesus, but someone who interviewed eyewitnesses and compiled reliable testimony (Luke 1:1–4).

Why that matters for Luke 2:8–11
– The scene (angels announcing the birth of Jesus to shepherds) fits Luke’s characteristic emphases: concern for the humble and marginalized (shepherds), the universal scope of salvation, and the clear proclamation of Jesus’ identity and saving role.
– The phrase “a Savior, who is Christ the Lord” expresses core evangelical convictions: Jesus is Savior (Soteriology), the promised Messiah (Christ), and Lord (kurios) — implying his authority and divinity.
– Evangelicals tend to treat Luke’s narrative as historically trustworthy and theologically purposeful: Luke records real events that carry salvific significance.

Date and reliability
– Many evangelical scholars date Luke–Acts around the time of Paul’s imprisonment (often ca. AD 60–62), though some allow somewhat later dates. Evangelicals generally argue for Luke’s historical reliability, supported by internal coherence, early attestation, and corroboration in places by archaeology and contemporary sources.

Practical note
– From an evangelical standpoint, Luke 2:8–11 shows God announcing good news to ordinary, lowly people — a pattern Luke emphasizes throughout: the gospel is for everyone, and Jesus is the promised Savior and Lord.