What does Acts 15:18 mean?

James finishes his paraphrased quote of Old Testament prophecy with a phrase that probably should have been combined with Acts 15:17. Chapter and verse divisions were added to translations of the Bible many centuries later to help modern readers locate passages. These markers have become accepted and standardized, but are not always in ideal places.

James is speaking to a council made up of the apostles and elders of the church of Jerusalem, Jewish Jesus-followers who still carry their Pharisaical legalism, and representatives from the mostly Gentile church in Syrian Antioch. The group has come together to decide if Gentiles must convert to Judaism before they can worship Jesus, the Jewish Messiah. Peter, Paul, and Barnabas have already given their testimony. They have eye-witness accounts of the Holy Spirit falling on Gentiles without so much as a baptism or laying on of hands, let alone circumcision. Now, James, as the pastor of the church of Jerusalem, gives his conclusion (Acts 15:1–14).

In Acts 15:15, James states "the words of the prophets agree." He then combines quotes from Amos 9:11–12, Jeremiah 12:15, and Isaiah 45:21 in the Septuagint to make one point: God promised that Gentiles would one day worship Him alongside Jews.

Acts 15:16 mostly quotes Amos 9:11. It speaks of God's promise to rebuild David's kingdom—"the tent of David"—referring to the Davidic covenant in which God promised David that his descendant would sit on his throne forever (1 Chronicles 17:11–14). James makes a slight adjustment, however, replacing "On that day" of the Septuagint with "After [this] I will return" from Jeremiah 12:15. Acts 15:17 quotes Amos 9:12, except the synecdoche "Edom" is simplified to the literal "remnant of mankind," and "who does these things" is replaced with a variation of "who made from the beginning these things that are to be heard" from Isaiah 45:21, also from the Septuagint.

In his quotes from the prophets, James' point is simple: God let it be known in the prophets—the Jewish Scriptures—that Gentiles would join Jews in worshiping Him, being His people, called in His name. Any Scripture-reading Jew—which the Pharisees were—should know this. There is no reason to be surprised that Gentiles would want to follow the Jewish Messiah.

James agrees with Peter that Jews have no right to place burdens on Gentiles (Acts 15:10, 19). God called Gentiles as Gentiles, not as Jewish converts. Therefore, they should not need to be circumcised or in any other way follow the Mosaic law. However, James understands that the conflict goes deeper: how can Jewish Christians, who believe Jesus is the fulfillment of Judaism and who still consider themselves devout Jews, have community with Gentiles? James concludes that for unity—not for salvation—Gentiles should refrain from sexual immorality and alter their diet so that Jews feel comfortable sharing a meal. The "requests" are reasonable; he tells them to avoid food that has been offered to pagan gods and from blood. The church agrees, and a letter goes out to the churches, to the relief of the Gentile believers (Acts 15:19–35).