Ex Opere Operato

I mentioned on a post earlier that a priest (however unworthy to stand in persona Christi) can validly confer the sacraments and the grace thereof, simply by being ordained a minister of the Church. What is the theological justification for this? Can something pure come from an impious source? Can salvation come through the hands of a servant of the evil one? An error has already been commited in these terms. The source is not the minister but it is Christ who operates by conferring his grace freely.
But is this a necessary destinction? Is this question one simply for the academics, the theologians or anyone who has enough time to contemplate trivialities? No.

The sacraments are vital for our salvation. This is no mere 'triviality'. Saint Thomas Aquinas writes that ''the sacrament of Baptism is said to be necessary for salvation in so far as man cannot be saved without, at least, Baptism of desire'' and the Doctrine of Grace adds, ''which, with God, counts for the deed'' (St. Augustine, Enarr. in Ps lvii). This is no mere opinion, as the Council of Trent confirms, ''If anyone says that baptism is optional, that is, not necessary for salvation. let him be anathema' (Canon 5 on Baptism). Or as our Lord states, that a man must be born again of water and the Spirit if he wish to enter the Kingdom of Heaven.
The lack of reception of this sacrament, the door to the New Ark, that is, the Church, may lead to eternal death, therefore showing that the valid addministration is of vital importance.

Back to the matter at hand. Let us in our discussion follow the Summa Theologica as usual.

The question, the Angelic Doctor brings first is ''Whether God Alone, Or The Minister Also, Works Inwardly Unto The Sacramental Effect?''(III Q64, A1). Thomas choose the first option and goes on in his answer to make a distinction between a 'principal agent' and an 'instrumental agent'. Principle means the first term of something. If this first term were not present, nothing else would follow. ''Instrumental'' means that something is itself used in order to bring about an effect. For example, if I picked up this red pen on my desk to write 'Filioque', the pen would be the instrument, whereas my hand would be the true cause (the principle cause). As without the motion of my hand, the pen would remain stationary. It would remain 'lifeless' and unable to write anything on the paper. The efficacy of this writing implement entirely depends upon my action. However, in human beings, we have something different at work. The pen simply works as that is what it is meant to do, unless there be some defect in it (lack of ink etc), on the other hand, human beings having a will can operate in a manner contrary to the divine will.
The Saint quotes from The Apostle and says that ''God justifieth'' (Rom. 8:33), and goes on to say, ''since, then, the inward effect of all the sacraments is justification (that is, making a man righteous (my addition)), it seems that God alone works the interior sacramental effect.''
The mere actions of a man (being a priest, uttering 'Hoc est enim corpus meum' with the intention to consecrate)have no effect unless it is God who confers His grace. The actions of the priest are simply like that of the red pen I mentioned earlier. The priest's words and intentions would remain 'lifeless' and fruitless, unless Christ acting upon His promise to stay with His Church for all time, and instituting the sacraments of the New Law is present invisibly. Although, like the fault in the pen, a defect may be on the part of the minister, not his personal holiness (or lack of it) but the use of the incorrect words or a flawed intention. This is the only obstacle that can be placed in the way.
Does this mean that the minister is merely a puppet in the hands of the Supreme Deity? No. The Dominican states that although the ''sacramental effect is made no better by a better minister' (Christ for example in the Sacrament of the Eucharist, is made no less present by an unworthy minister), however 'something in addition may be impetrated for the receiver through the devotion of the minister: but this is not the work of the minister, but the work of God who hears the minister's prayer''.

The Council of Trent, in reply to the protestant heretics stated that the term 'ex opere operato' (through the work that is worked, from Canon 8 of the Seventh Session), shows the Catholic teaching on this matter.

This matter came to the forefront at the Donatism schism, and it was through the work of the great Saint Augustine, that the Catholic position became more thorough and clear.

In conclusion, as long as the correct intention is present and the proper words are used by a minister authorised (in virtue of his ordination for certain sacraments, or faculties by the local ordinary), the grace will be conferred, even if he be(or she in the case of baptism), a sexual monster, an unbeliever, a modernist or the most holy person this side of heaven.