ISB ~ John 10 v16

other sheep:A reference to the Gentiles, who are gathered into the Messiah’s flock alongside the restored sheep of Israel (11:52). one flock, one shepherd: Jesus Christ is the supreme Shepherd over the one universal Church (Heb 13:20). The spiritual authority of other shepherds like Peter and the apostles is derived entirely from Christ, who gives disciples a share in his saving mission to different degrees (21:1517; CCC 553, 754).

• The Nicene Creed delineates the four marks of the Church as “one, holy, catholic, and apostolic”. The first mark, oneness, means that the Church is unified in her faith, worship, and leadership and receives her life from the one true God (17:11; Eph 4:4-6) (CCC 813-22).