While the teaching of the Church reflects the principles of Natural Law, it also extends to those baptized, certain particular obligations and duties which arise from their baptism. “Holy Baptism is the basis of the whole Christian life, the gateway to live in the Spirit and the door which gives access to the sacraments. Through Baptism we are freed from sin and reborn as sons of God; we become members of Christ, are incorporated into the Church and made sharers in her mission: ‘Baptism is the sacrament of regeneration through water and in the word.’” (Catechism of the Catholic Church, 1213)
When we speak of marriage being a sacrament, we are presupposing that both of the parties of the marriage are baptized. The sacrament can only be received by one who is baptized. When both parties are baptized, they confer on one another the sacrament of marriage. Let us now consider the situation when one of the parties is not baptized. Although it is not a sacramental marriage, it is a natural, legitimate and valid marriage. In virtue of his authority as the Vicar of Christ, the Holy Father has the jurisdiction to set aside the union of a couple when one has not been baptized. In this dissolution of the natural bond, which is sometimes call the Petrine Privilege, it must be established that one of the parties to the original marriage was not baptized. When this fact can be shown with certainty, it follows that the marriage in this circumstance is not a sacrament. When this is the case, and in certain circumstances, a petition can be placed before the Holy Father asking that the former union be dissolved in favor of the faith of the Catholic party who is now involved.