The Second Vatican Council presents the Church as Christ’s light and as a sign and instrument of union with God and humanity. It traces the Church’s origin through God’s saving plan, Christ’s Kingdom, and the sanctifying action of the Holy Spirit; describes its visible and spiritual dimensions, its unity, holiness, catholicity, and apostolicity; and explains the People of God, the common and ministerial priesthood, the sensus fidei, missionary responsibility, and the Church’s relation to other Christians and to Jews, Muslims, and those who have not heard the Gospel.

The constitution defines the apostolic college, the primacy and infallibility of the Roman Pontiff, the ministry of bishops, priests, and deacons, and the distinctive vocation of the laity to sanctify the world through family, work, and public life. It calls every Christian to holiness, treats religious life as a sign of the coming Kingdom, and describes the communion of the faithful on earth, in purification, and in heaven. Its final chapter presents Mary’s motherhood, cooperation in salvation, perpetual virginity, Immaculate Conception, Assumption, intercession, and exemplary holiness, while directing Marian devotion toward Christ. The appended explanatory note clarifies that episcopal collegiality always includes the Pope as its head and depends on hierarchical communion and juridical determination.