The Eucharist and True Sacrifice
A true sacrifice is every work which is done that we may be united to God in holy fellowship, and which has a reference to that supreme good and end in which alone we can be truly blessed. And, therefore even the mercy we show to men, if it is not shown for God's sake, is not a sacrifice. For, although made or offered by man, sacrifice is a divine thing, as those who called it sacrificium meant to indicate.[1] Thus man himself, consecrated in the name of God, and vowed to God, is a sacrifice in so far as he dies to the world that he may live to God.
For this is a part of that mercy which each man shows to himself; as it is written, “Have mercy on your soul by pleasing God” (Sir. 30:24). Our body, too, is a sacrifice when we chasten it by temperance, if we do so as we ought, for God's sake, that we may not yield our bodily members to be instruments of unrighteousness unto sin, but to be instruments of righteousness unto God (Rom. 6:13) Exhorting to this sacrifice, the apostle [Paul] says, “I beseech you, therefore, brethren, by the mercy of God, that you present your bodies a living sacrifice, holy, acceptable to God, which is your reasonable service [i.e. sacrifice]” (Rom. 12:1). If, then, the soul uses the body, which is inferior, as a servant or instrument, and it is a sacrifice to God when it is used rightly, how much more does the soul itself become a sacrifice when it offers itself to God, in order that, being inflamed by the fire of his love, it may receive of His beauty and become pleasing to Him, losing the shape of earthly desire, and being remoulded in the image of permanent loveliness? Indeed, the apostle [Paul] exhorts us to do this, saying, “And be not conformed to this world; but be transformed in the renewing of your mind, that you may prove what is that good, and acceptable, and perfect will of God” (Rom. 12:2).
Therefore, true sacrifices are works of mercy done to ourselves or to others, and done with a reference to God. And, since works of mercy have no other object than the relief of distress or the conferring of happiness, and since there is no happiness apart from that good of which it is said, “It is good for me to be very near to God” (Ps. 73:28), it follows that the whole redeemed city, that is to say, the congregation or community of the saints, is offered to God as our sacrifice through the great High Priest, who offered Himself to God in His passion for us, that we might be members of this glorious head, according to the form of a servant. For it was this form of a servant that he offered, and in this he was offered, because it is according to it that he is Mediator, in this he is our Priest, in this the Sacrifice.
Accordingly, when the apostle [Paul] had exhorted us to present our bodies a living sacrifice, holy, acceptable to God, our reasonable service, and not to be conformed to the world, but to be transformed in the renewing of our mind, that we might prove what is that good, and acceptable, and perfect will of God, that is to say, the true sacrifice of ourselves, he says, “For I say, through the grace of God which is given unto me, to every man that is among you, not to think of himself more highly than he ought to think, but to think soberly, according as God has dealt to every man the measure of faith. For, as we have many members in one body, and all members have not the same office, so we, being many, are one body in Christ, and every one members one of another, having gifts differing according to the grace that is given to us” (Romans 12:3-6). So this is the sacrifice of Christians: we, being many, are one body in Christ. And this also is the sacrifice which the Church continually celebrates in the sacrament of the altar, known to the faithful, in which she teaches that she herself is offered in the offering she makes to God.