The sacraments serve: (1) as sources of grace for individuals and communities and (2) as remedies for sin and the effects of sin. The sacraments are also signs of faith, as explained in question 192.
1. The sacraments serve as sources of grace for individuals and communities.
All the sacraments produce sanctifying grace. In addition, each sacrament gives its own particular actual graces and a right to future actual graces. The graces given benefit not only the person who receives the sacrament, but also the entire community of faith. The sacraments are instruments of divine life for the family of God.
2. The sacraments serve as remedies for sin and the effects of sin.
The sacraments are remedies for sin and the effects of sin. Mortal sin is the greatest evil in the world because it drives the supernatural life of sanctifying grace out of our souls and turns us away from God, the source of all life, peace, and joy. Our Lord protects our souls from serious sin by giving us more sanctifying grace in the sacraments.
The actual graces we receive through the sacraments give us the light we need to see what is evil and the strength we need to fight against it. Thus, we are strengthened against temptation.
This is especially true of the Holy Eucharist. Just as bodily food repairs what we lose by daily wear and tear, so likewise this divine food is a remedy for the spiritual infirmities of each day. The sacramental grace we receive in the Eucharist is a remedy for our spiritual sicknesses and for all the effects of sin.