The Sacrament of Holy Communion is the third of the Sacraments of Initiation. Even though we are required to receive Communion at least once per year (our Easter Duty), and the Church urges us to receive Communion frequently (even daily, if possible), it is called a sacrament of initiation because, like Baptism and Confirmation it brings us into the fullness of our life in Christ.
In Holy Communion, we are eating the True Body and Blood of Jesus Christ, without which “you shall not have life in you” (John 6:53). Because of the intimate connection of the Sacrament of Holy Communion to our life in Christ, we must be free of any grave or mortal sin before receiving it, as St. Paul explained in 1 Corinthians 11:27-29: “Therefore whoever eats the bread or drinks the cup of the Lord unworthily will have to answer for the body and blood of the Lord. A person should examine himself, and so eat the bread and drink the cup.”
If we are aware of having committed a mortal sin, we must participate in the Sacrament of Reconciliation first. The Church sees the two sacraments as connected, and urges us, when we can, to join frequent Confession with frequent Communion.
Making a Spiritual Communion
If we cannot receive Holy Communion physically, either because we cannot make it to Mass or because we need to go to Confession first, we can pray an Act of Spiritual Communion, in which we express our desire to be united with Christ and ask Him to come into our soul. A spiritual communion is not sacramental, but prayed devoutly, it can be a source of grace that can strengthen us until we can receive the Sacrament of Holy Communion once again.
Receiving Holy Communion worthily brings us graces. Our souls become more united to Christ, both through the graces we receive and through the change in our actions that those graces effect. Frequent Communion increases our love for God and for our neighbor, which expresses itself in action, which makes us more like Christ.
Physically, “A final effect of Communion is to remove the personal guilt of venial sins, and the temporal [earthly and purgatorial] punishment due to forgiven sins, whether venial or mortal.”