We learn to know, love, and serve God from Jesus Christ, the Son of God, who teaches us through the Catholic Church. In order to be saved, all persons who have attained the use of reason must believe explicitly that God exist and that he rewards the good and punishes the wicked; in practice they must also believe in the mysteries of the Blessed Trinity and the Incarnation. By the Blessed Trinity we mean one and the same God in three divine persons, the Father, the Son, and the Holy Ghost. By the Incarnation is meant that the Son of God, retaining His divine nature, took to Himself a human nature, that is, a body and soul like ours.
The Church is the congregation of all baptized persons united in the same true faith, the same sacrifice, and the same sacraments, under the authority of the Sovereign Pontiff and the bishops in communion with him.