Note 7 at Eph. 4:4: Disunity among believers was unacceptable to the apostle Paul. He made this a major issue in his letter to the Corinthians (see ref. e at v. 3, this page). The reasons for his intolerance of disunity are listed in verses 4-6.

We all are "one body" in Jesus Christ. We all have "one Spirit" giving us life. We all have the same "hope" of seeing Christ and being transformed into his likeness. We all have "one Lord" who is our Master. There is only "one faith" in Christ and His atonement and "one baptism" into Jesus Christ. We are all one family because we all share "one God and Father." One God is above all, through all (i.e. that is working through us), and in us all (indwelling every believer).