CCC 1271 Baptism constitutes the foundation of communion among all Christians, including those who are not yet in full communion with the Catholic Church: “For men who believe in Christ and have been properly baptized are put in some, though imperfect, communion with the Catholic Church. Justified by faith in Baptism, [they] are incorporated into Christ; they therefore have a right to be called Christians, and with good reason are accepted as brothers by the children of the Catholic Church.”¹ “Baptism therefore constitutes the sacramental bond of unity existing among all who through it are reborn.”²

1 UR 3.
2 UR 22 # 2.