Why does Paul use the word “mystery” so often in his letter to the Ephesians?

Today Bible Study:

Why does Paul use the word “mystery” so often in his letter to the Ephesians?

Paul actually uses the word “mystery” six times in this letter (1:9; 3:3, 4, 9; 5:32; 6:19). By comparison, the word appears twice in Romans, once in 1 Corinthians, four times in Colossians, once in 1 Timothy, and nowhere else. Contrary to our use of “mystery” as a series of clues to be figured out, Paul’s use of the word points to mystery as a heretofore unrevealed truth that has been made clear. The word “mystery” preserves the sense that the revealed truth has such awesome implications that it continues to amaze and humble those who accept it.

Ephesians introduces various aspects of the “mystery.” Paul explained his use of the word in 3:4–6 by saying, “that the Gentiles should be fellow heirs, of the same body, and partakers of His promise in Christ through the gospel.” When the unsearchable riches of Christ are preached among the Gentiles, one result is an understanding of the “fellowship of the mystery” (3:9). And when God’s plan for human marriage is used to explain the unique relationship between Christ and His bride, the church, Paul reminded his readers that the real subject is a great mystery (5:32). And finally, Paul asked the Ephesians to pray for him that he would be able “boldly to make known the mystery of the gospel” (6:19).The gospel is not mysterious because it is hard to understand. It is mysterious because it is unexpected, unmerited, and free. Though Paul didn’t use the word in this passage, his summary of the mystery for the Ephesians can be found in 2:8,9:“For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, not of works, lest anyone should boast.”