Old covenant practices cannot be imposed on the new (Mat 9:14-17). There's a radical difference between the body of Christ and "gentiles" (Eph 4:17-19): "futility of the mind", vacuum of soul, ignorance, licentiousness, and frantic search for happiness. We are in the school of Christ since understanding the gospel (Eph 4:20, Eph 1:13). The topic is the teacher; Christ is the teacher (Eph 4:21, Joh 14:6). School membership is exclusive (Mat 23:8). The instructor's teachings are absolutely authoritative (Joh 6:45, Joh 8:28). We have a personal mentor - the Holy Spirit (Joh 15:26, Joh 16:13-14, 1Jo 2:27). We have to give the Mentor permission (Col 3:16).
More than any book Ephesians reveals the blessings from God based on our relationship with Jesus Christ by grace through faith. Eph 1:3 is the a key verse. Other key verses by chapter include Eph 2:8 Eph 3:19 Eph 4:1 Eph 5:18 and Eph 6:10-11.