What does Acts 20:27 mean?

Elders of the church of Ephesus are being reminded how faithfully Paul ministered to them. He dedicated three years of his life to teaching how people could receive forgiveness from their sins by trusting in Jesus (Acts 20:31). Yet, he went beyond the simple message of salvation and taught them everything they needed to follow God.

He began years before. On his way back from his second missionary journey, Paul briefly stopped in Ephesus. He attended the synagogue and "reasoned" with the people there, most likely showing how Jesus fulfills the prophecies of the Messiah as recorded in the Old Testament. The congregation asked him to return, and he promised he would if he could (Acts 18:19–21).

During his third journey, Paul stayed for three years (Acts 20:31). Very soon after he arrived, he found twelve men who followed the message of John the Baptist. They dedicated their lives to the belief that God would honor their sincere repentance from their sins and that the Messiah was coming soon. Paul completed John's message by explaining that Jesus of Nazareth is that Messiah (Acts 19:1–7).

Paul then spent three months teaching about the kingdom of God at the local synagogue. Many believed, but some rejected his message and pushed him out. Paul moved to a local hall and continued teaching. In that time, the news about Jesus reached all over the province of Asia in southwest modern-day Turkey (Acts 19:8–10).

The New International Version uses "the whole will of God" while the New American Standard Bible uses "the whole purpose of God." Primarily, Paul taught everything they needed to know to be saved from their sins, including that forgiveness is through Jesus, alone, and not through works (Ephesians 2:1–10). He also taught them how to fight against the rampant witchcraft in the city by remembering who their enemy is and putting on the armor of God (Acts 19:18–19; Ephesians 6:10–20)—a lesson they will cling to for decades (Revelation 2:2–3).