I was in a discussion with a friend recently about the “necessary minimum requirements” of Catholics. What are these minimum requirements?
It sounds like you’re referring to the precepts of the Church. The Catechism explains that the precepts are meant to guarantee us “the very necessary minimum in the spirit of prayer and moral effort, in the growth in love of God and neighbor” (2041). Here they are as the Catechism currently lists them (2042-2043):
The first precept (“You shall attend Mass on Sundays and holy days of obligation and rest from servile labor”) requires the faithful to sanctify the day commemorating the Resurrection of the Lord as well as the principal liturgical feasts honoring the mysteries of the Lord, the Blessed Virgin Mary, and the saints; in the first place, by participating in the eucharistic celebration, in which the Christian community is gathered, and by resting from those works and activities which could impede such a sanctification of these days.
The second precept (“You shall confess your [serious] sins at least once a year”) ensures preparation for the Eucharist by the reception of the sacrament of reconciliation, which continues baptism’s work of conversion and forgiveness.
The third precept (“You shall receive the sacrament of the Eucharist at least once during the Easter season”) guarantees as a minimum the reception of the Lord’s body and blood in connection with the Paschal feasts, the origin and center of the Christian liturgy.
The fourth precept (“You shall observe the days of fasting and abstinence established by the Church”) ensures the times of ascesis and penance which prepare us for the liturgical feasts and help us acquire mastery over our instincts and freedom of heart.
The fifth precept (“You shall help to provide for the needs of the Church”) means that the faithful are obliged to assist with the material needs of the Church, each according to his own ability. (CCC 2042-2043)