Rather than just provide a simple answer, we should begin by briefly reflecting on the mystery of the Holy Mass. At the Last Supper, Jesus instituted the precious gift of the Holy Eucharist. His words and actions were indeed sacrificial: He said not only, “this is my Body,” but also, “which is given for you”; and not only, “this is my Blood,” but also, “which is poured out for you.” Here, our Lord instituted sacramentally the sacrifice for our sins that would be enacted on Good Friday and offered on the cross.
So the Holy Mass represents, in an unbloody, sacramental way Christ’s sacrifice. Blessed Pope John Paul II taught, “the Mass makes present the sacrifice of the Cross; it does not add to the sacrifice nor does it multiply it. What is repeated is its memorial celebration, its ‘commemorative representation,’ which makes Christ’s one, definitive redemptive sacrifice always present in time. The sacrificial nature of the eucharistic mystery cannot therefore be understood as something separate, independent of the Cross or only indirectly referring to the sacrifice of Calvary” (“Ecclesia de Eucharistia,” No. 12).
With this understanding, the Catechism asserts two important points: “Holy Communion augments our union with Christ” (#1391) and “Holy Communion separates us from sin” (No. 1393). Since the Holy Mass represents our Lord’s sacrifice for sin, and the Holy Eucharist unites us with our Lord, receiving the Holy Eucharist must both cleanse us of venial sin and protect us from future sin. The Council of Trent’s, Decree on the Holy Eucharist (Chapter II) taught, “…(The Holy Eucharist) be also a remedy to free us from our daily faults and to preserve us from mortal sin.” (See also No. 231).
The church fathers also taught this belief: For example, St. Ambrose preached, “For as often as we eat this bread and drink the cup, we proclaim the death of the Lord. If we proclaim the Lord’s death, we proclaim the forgiveness of sins. If, as often as His Blood is poured out, it is poured for the forgiveness of sins, I should always receive it, so that it may always forgive my sins. Because I always sin, I should always have a remedy.” Similarly in the Divine Liturgy of St. John Chrysostom, the priest prays: “We beseech, implore, and beg you: send your Holy Spirit upon us all and upon these gifts… that those who partake of them may be purified in soul, receive the forgiveness of their sins, and share in the Holy Spirit.”
However, if a person is conscious of mortal sin, he must make a sincere confession and receive sacramental absolution before receiving the Holy Eucharist. Since mortal sin destroys sanctifying grace in a person’s soul, the sacrament of penance is necessary to reconcile the sinner and restore sanctifying grace before receiving holy Communion. If a person receives holy Communion in a state of mortal sin, he commits a sacrilege, which in itself is a mortal sin.
Nevertheless, even if a person is not conscious of a mortal sin, regular reception of the sacrament of penance is a good spiritual practice. Blessed Pope John Paul II taught: “It would, therefore, be foolish, as well as presumptuous, to wish arbitrarily to disregard the means of grace and salvation which the Lord has provided and, in the specific case, to claim to receive forgiveness while doing without the sacrament which was instituted by Christ precisely for forgiveness” (On Reconciliation and Penance, No. 31). Consequently, a faithful Catholic must never discount the spiritual exercise of confession, from beginning to end: to examine one’s conscience, to have contrition (i.e. sorrow for sin), to make a firm amendment not to sin again, to confess one’s sins, and to receive absolution and the graces that heal the soul of sin, restore fully sanctifying grace, and fortify it against future temptation. Regular confession of venial sin helps the individual to form his conscience better, fight against temptation, be aware of the occasions of sin, and progress in the life of the Holy Spirit (cf. catechism 1458).
Regular confession is the recipe for sainthood, and all of the saints of our church not only knew it but advocated it. Blessed Mother Teresa of Kolkata and Blessed Pope John Paul II both received the sacrament of penance at least weekly. They were so in love with the Lord that they were mindful of the smallest violation of that love and did not want even the least venial sin to impair their relationship with Him. As we draw closer to Easter, who of us would be so proud that we would refrain from receiving the graces of the sacrament of penance?