FOURTH ARTICLE [III, Q. 80, Art. 4]
Whether the Sinner Sins in Receiving Christ's Body Sacramentally?
Objection 1: It seems that the sinner does not sin in receiving Christ's body sacramentally, because Christ has no greater dignity under the sacramental species than under His own. But sinners did not sin when they touched Christ's body under its proper species; nay, rather they obtained forgiveness of their sins, as we read in Luke 7 of the woman who was a sinner; while it is written (Matt. 14:36) that "as many as touched the hem of His garment were healed." Therefore, they do not sin, but rather obtain salvation, by receiving the body of Christ.
Obj. 2: Further, this sacrament, like the others, is a spiritual medicine. But medicine is given to the sick for their recovery, according to Matt. 9:12: "They that are in health need not a physician." Now they that are spiritually sick or infirm are sinners. Therefore this sacrament can be received by them without sin.
Obj. 3: Further, this sacrament is one of our greatest gifts, since it contains Christ. But according to Augustine (De Lib. Arb. ii), the greatest gifts are those "which no one can abuse." Now no one sins except by abusing something. Therefore no sinner sins by receiving this sacrament.
Obj. 4: Further, as this sacrament is perceived by taste and touch, so also is it by sight. Consequently, if the sinner sins by receiving the sacrament, it seems that he would sin by beholding it, which is manifestly untrue, since the Church exposes this sacrament to be seen and adored by all. Therefore the sinner does not sin by eating this sacrament.
Obj. 5: Further, it happens sometimes that the sinner is unconscious of his sin. Yet such a one does not seem to sin by receiving the body of Christ, for according to this all who receive it would sin, as exposing themselves to danger, since the Apostle says (1 Cor. 4:4): "I am not conscious to myself of anything, yet I am not hereby justified." Therefore, the sinner, if he receive this sacrament, does not appear to be guilty of sin.
On the contrary, The Apostle says (1 Cor. 11:29): "He that eateth and drinketh unworthily, eateth and drinketh judgment to himself." Now the gloss says on this passage: "He eats and drinks unworthily who is in sin, or who handles it irreverently." Therefore, if anyone, while in mortal sin, receives this sacrament, he purchases damnation, by sinning mortally.
I answer that, In this sacrament, as in the others, that which is a sacrament is a sign of the reality of the sacrament. Now there is a twofold reality of this sacrament, as stated above (Q. 73, A. 6): one which is signified and contained, namely, Christ Himself; while the other is signified but not contained, namely, Christ's mystical body, which is the fellowship of the saints. Therefore, whoever receives this sacrament, expresses thereby that he is made one with Christ, and incorporated in His members; and this is done by living faith, which no one has who is in mortal sin. And therefore it is manifest that whoever receives this sacrament while in mortal sin, is guilty of lying to this sacrament, and consequently of sacrilege, because he profanes the sacrament: and therefore he sins mortally.
Reply Obj. 1: When Christ appeared under His proper species, He did not give Himself to be touched by men as a sign of spiritual union with Himself, as He gives Himself to be received in this sacrament. And therefore sinners in touching Him under His proper species did not incur the sin of lying to Godlike things, as sinners do in receiving this sacrament.