“One of the most notable features in this eschatological people is that of fellowship (koinonia). Fellowship was one of the distinctive marks of the Jerusalem church (Acts 2:42).
This is something more than human fellowship or the pleasure people of like mind find in each other’s presence. It is more than a fellowship in a common religion. It is an eschatological creation of the Holy Spirit. Probably II Corinthians 13:14 should be rendered “the fellowship created by the Holy Spirit”; and Philippians 2:1 may be rendered “if the Spirit has really created a fellowship/” This relationships exists between people because they share a common relationships to Christ (1 Cor. 1:9). A bond exists between all who are in Christ that is unique and transcends all other human relationships. From the divine side, those who have entered this fellowship do so because they have been called of God (1 Cor. 1:9). The church is a fellowship of the elect (Eph. 1:4; 1 Thess. 1:4), regardless of social status, education wealth or race (1 Cor. 1:27). The church can be designated simply as the elect of God (Rom. 8:33; Col. 3:12; II Tim. 2:10; Titus 1:1). This emphasizes the fact that the church is not primarily a human institution nor a religious movement founded on good works or event allegiance to a great teacher or leader; it is a creation of God based on his gracious purpose (Rom. 9:11; 11:5-6).”
–George Eldon Ladd, A Theology of the New Testament, page 543