How Do The Sacraments Work?

You may have heard it said that the Sacraments work ex opere operato. But what does this mean?

Ex Opere Operato – Basic Explanation

In Sacramental Theology, the Church teaches that the Sacraments work according to the principle ex opere operato (in Latin, “from the work performed”). This teaching is de fide (of the faith). It is an expression immortalized by the dogmatic teaching of the Council of Trent. 

This simply means that by the very act of the rite being performed correctly (i.e., according to the Church’s established rubrics), we have the divine guarantee that God offers the sanctifying grace promised in the respective sacrament. 

The sacrament is not just a ‘sign’ that the sanctifying grace was previously given. The sacrament does not ‘work’ by inspiring faith in a believer. Rather, God gives the grace signified by the rite as the act is being performed because man is obeying Him by performing the act. God freely chooses to do this. He has promised to do this and binds Himself by His own oath.[1]

Deepening the Explanation

Thus, provided there is no obstacle placed in the way (e.g., invalid matter or form, absence of right intention on the part of the minister), every Sacrament properly administered confers the grace intended by the Sacrament. The reception of a Sacrament does not depend on the sanctity of the individual priest conferring it since it is ultimately Christ Himself Who confers grace through each Sacrament. 

St. Augustine famously rebutted the Donatist heretics by stating: “If Peter baptizes, it is Christ who baptizes. If Judas baptizes, it is still Christ who baptizes.” This captures the essence of ex opere operato in a pithy statement easy for us to memorize and repeat. It also shows this theological principle was accepted in antiquity. St. Thomas Aquinas (1225-1274) reiterates this teaching in his Summa Theologiae, “the sacrament is not perfected by the righteousness of the minister … but by the power of God.”[2]

We should be extremely grateful for this teaching, because otherwise we could never have any certitude regarding God’s sacramental grace. We would always remain in doubt if our baptism had really washed away original sin or if our sins had truly been absolved in confession. This guarantee is only possible because the Church who performs the sacraments is indeed the Mystical Body of Christ.

We see this principle often discussed in relation to the Sacrament of the Most Holy Eucharist in the context of the Holy Sacrifice of the Mass. The effects of the Mass which relate immediately to God, such as reparatory adoration and thanksgiving, are always infallibly and wholly produced with their infinite value so long as the Mass is valid. The effects of the Mass which relate to us are poured forth on us only in the measure of our interior dispositions. The sacrifice of the Mass, as a sacrifice of satisfaction, also infallibly remits to repentant sinners at least a part of the temporal punishment due to sin in proportion to their dispositions. As an act of supplication, the Mass obtains for us ex opere operato all the graces we need for our sanctification. 

Note, the priest might not believe in the dogma of transubstantiation, but so long as he uses the proper matter and form and intends what the Church intends, then the bread and wine will be turned into the Body and Blood of Christ at the words of consecration. We commonly refer to this as a ‘valid’ sacrament. 

Even worse, if the priest intentionally wants to commit sacrilege and desecrate the Holy Eucharist, God will nonetheless turn the bread and wine into His Body and Blood if the priest employs the proper matter, form and intent to consecrate. How this manifests the great and incomprehensible humility of God! It also shows the power behind the teaching ‘ex opere operato.

The Grace Signified

Each sacrament signifies certain sacramental graces. This signification is expressed by the matter and form used for each sacrament. That is, we look to the words being said, the matter being used (e.g., water, oil or bread), and the acts which make up the rite to know what grace[s] each sacrament confers. 

For example, in Baptism water signifies the manifold graces of the Sacrament. Water is naturally used to cleanse. All the stain of sin – original and actual – is being washed away. Water is also capable of bringing about death. The creature is dying to sin with Christ. We are born from a womb filled with water. So too, in Baptism we are reborn as adopted children of God from the waters of the baptismal font, representing the womb of Holy Mother Church. Water is also necessary for life, just as God’s sanctifying grace – which we receive at Baptism – is necessary for supernatural life.

The teaching ‘ex opere operato’ is so essential because it preserves the objective truth that a specific sanctifying grace is guaranteed to be conferred by God when the sacrament is performed validly. Yes, the rite must be performed correctly, and in turn the corresponding grace is given. Here we do well to recall the words of Our Lord at the Last Supper: “Whatsoever you shall ask the Father in My Name, that will I do: that the Father may be glorified in the Son” (John 14:13).

Objective vs. Subjective

However, there is an important distinction between the objective reality of sanctifying grace being conferred and its subjective effects within each individual recipient. ‘Ex opere operato only addresses the objective dimension. How each subject chooses to cooperate with – or not cooperate with – the grace received depends on one’s interior disposition, habitual virtues, and free will. This truth is better expressed by the twin principle of ‘ex opere operantis.’ That will be the subject of a forthcoming article.


[1] As Fr. John Hardon (1914-2000) explains in his Modern Catholic Dictionary, the Fathers of Trent dogmatically defined that grace is always conferred by a Sacrament “in virtue of the rite performed and not as a mere sign that grace has already been given, or that the sacrament stimulates the faith of the recipient and thus occasions the obtaining of grace, or that what determines the grace is the virtue of either the minister or recipient of a sacrament.”

[2] Summa Theologiae, III, q. 68, a. 8 (

Print Friendly, PDF & Email