Short answer
– From an evangelical Christian perspective, the most‑likely author of Matthew 7:12 is the apostle Matthew (also called Levi), the former tax collector who became one of Jesus’ twelve disciples and an early eyewitness to Jesus’ ministry. Matthew is traditionally regarded as the author of the Gospel that bears his name.

Who Matthew was (brief biography)
– Identity: Matthew the tax collector (see Matthew 9:9; Luke 5:27–28), listed among the twelve apostles (Matthew 10:3).
– Background: A Jewish follower of Jesus who left his job to follow the Lord. Evangelicals emphasize his calling as giving him eyewitness access to Jesus’ teachings.
– Later ministry: Church tradition portrays him as an early evangelist to Jewish and/or mixed Jewish-Gentile communities.

Why evangelicals attribute the Gospel to Matthew
– New Testament links: The man called Matthew in the Gospel narrative is identified as an apostle (internal links to the author are inferred).
– Early church testimony: Early Christian writers (e.g., Papias as reported by Eusebius, Irenaeus, Origen) explicitly attribute the Gospel to Matthew, and evangelicals regard this patristic testimony as trustworthy.
– Apostolic authority: Evangelicals often hold that the Gospel was written by an eyewitness or a close associate of eyewitnesses, giving it apostolic authority and historical reliability.

Date, language and place (evangelical view)
– Date: Common evangelical estimates place Matthew’s Gospel in the mid‑to‑late first century (often the 50s–70s AD; many favor the 60s).
– Language: The Gospel we have is in Greek. Early testimony (Papias) claims Matthew compiled sayings “in the Hebrew dialect,” which evangelicals interpret variously: as an earlier Aramaic/Hebrew collection used by the evangelist, or as indicating Matthew’s Jewish background and dependence on Semitic sources, with the final product preserved in Greek.
– Place of composition: Often thought to be written for Jewish Christians, possibly from Antioch or another Syrian/Jewish Christian center.

How that relates to Matthew 7:12
– Context: Matthew 7:12 (“So in everything, do to others what you would have them do to you; for this is the Law and the Prophets” — NIV wording) is part of the Sermon on the Mount (chapters 5–7), a collection of Jesus’ core ethical teachings.
– Evangelical interpretation: Because the Gospel is regarded as anchored in apostolic testimony, evangelicals view Matthew’s presentation of Jesus’ teaching here as authoritative, historically grounded, and theologically normative for Christian ethics.
– The verse’s significance: Evangelicals commonly see the “Golden Rule” as a succinct summary of the ethical intent of the Torah and the prophetic call to love one’s neighbor, not as a replacement of Scripture but as Jesus’ authoritative restatement and fulfillment of it (cf. Matthew 5:17).

Practical and theological emphases from an evangelical angle
– Jesus as authoritative teacher and fulfiller of the Old Testament.
– Jesus’ ethic is both demanding and rooted in love for God and neighbor.
– The Gospel of Matthew aims to show Jesus as Messiah and King, and to instruct his followers in discipleship — Matthew 7:12 is an example of practical guidance that flows from that identity.

A brief note on scholarly debates
– Many modern scholars discuss the Gospel’s anonymity, literary sources (Mark, Q, etc.), and editorial development. Evangelicals generally accept scholarly methods but typically affirm the traditional attribution to Matthew and the Gospel’s apostolic authority.

If you want, I can:
– Summarize early patristic evidence for Matthew’s authorship (Papias, Irenaeus, etc.).
– Give evangelical exegetical comments on Matthew 7:12 and how it has been applied in church history and contemporary life.