4:3 unity. It is noteworthy that the only references to Christian “unity” in the New Testament—in so far as the word itself is concerned—are here in this chapter. “The unity of the faith” (Ephesians 4:13) is vital, but so is “the unity of the Spirit.” There can be no real spiritual unity without doctrinal unity, and vice versa. In one sense, the two are synonymous, because sound doctrine includes the doctrine of the Holy Spirit and His “fruit” produced in the lives of true believers. Note also I Corinthians 1:10.

4:13 unity of the faith. See note on Ephesians 4:3. Also note Romans 16:17-18.

4:13 and. “And” could better be rendered “even.” That is, the unity of the faith is essentially synonymous with “the knowledge of the Son of God.”