4:3

maintain the oneness of the spirit: A Christian who applies this counsel will yield to the influence of God’s spirit and allow it to produce its fruitage. “The spirit” that comes from God is a powerful force that unites people. (1Co 2:12; Ga 5:22, 23) In the preceding verse, Paul mentioned humility, mildness, patience, and love​—qualities that promote unity.​—Eph 4:2.

the uniting bond of peace: The Greek word for “uniting bond” literally means “that which holds something together; fastener.” The word is used in its literal sense at Col 2:19, where it is rendered “ligaments,” the strong bands of tissue that join one bone to another. Like a ligament, peace forms a durable bond that joins the congregation members together. Such peace involves more than the absence of conflict. It is based on love and requires effort to maintain. (Eph 4:2) Paul uses the same Greek word at Col 3:14, where he calls love “a perfect bond of union.”