I have been studying Catholic theology lately, examining the major disagreements it has with my Protestant theology.
While there are major differences, things like the sinlessness of Mary, or the veneration of saints and icons, or papal authority, this was not the largest difference I saw. And to be honest, there are explanations for these practices that aren’t altogether outlandish (though I would still disagree).
Another difference that some might point out is how the Catholics view the sacraments. According to the Catholic Catechism, Catholics understand the sacraments to be “‘powers that comes forth’ from the Body of Christ, which is ever-living and life-giving”. In other words, Jesus himself gives life to his church in the sacraments. So in baptism, Jesus himself effects regeneration. In confirmation, Jesus gives the fulness of the Spirit. In the Eucharist, Christians quite literally are nourished by Jesus’ body. And this is because, according to Catholic theology, the church is a continuation of the incarnation of Christ. And through his body, in the sacraments, he saves his people. Nevertheless, Protestants, healthy ones at least, understand the importance of the sacraments, and that Jesus really does impart grace through them (although we would understand them differently of course).
I wouldn’t even see grace as the primary difference. All too often, Catholic theology is seen as works-based, religious, dry. However, every Catholic I know would deny that. In fact, grace is central to Catholic theology. The Catechism states that salvation “has been merited for us by the Passion of Christ who offered himself on the cross as a living victim, holy and pleasing to God, and whose blood has become the instrument of atonement for the sins of all men”. Who could disagree with that? Grace really is present in Catholic theology.
So then, what is the big difference?
To me, the thing that makes Protestants and Catholics diverge; the rub, as it were, is what “justification” means. Justification means two different things in Protestant and Catholic theology — did you know that?
For Protestants, justification is the declaration that sinners, though they be sinners, are righteous because of the righteousness of Christ. Because Christ was obedient in our place, on our behalf, we are given, or imputed Christ’s righteousness. We are saved by the righteousness of another, not our own. As Luther says, justification is the gift of an “alien righteousness, that is the righteousness of another, instilled from without. This is the righteousness of Christ by which he justifies through faith”. We are saved not because we are actually righteous (though we will be righteous in glory), but because Jesus is. So that is Protestant “justification”.
But Catholics do not see justification this way. Though they would still hold to justification, they would define it as the transference from being a child of wrath to being a child of God. And in this transference, rather than Christ’s righteousness being imputed, his righteousness is imparted, or infused within us. What they mean is that the merits of Christ are literally infused into our nature, thereby making us not legally righteous, but actually righteous. Andrew Preslar writes,
[J]ustification is an act of God by which the merits of Jesus Christ, sanctifying grace, and charity are communicated to sinners, who are thereby made just. This infused charity fulfills the righteous demands of the law, being “poured into our hearts through the Holy Spirit” (Romans 5:5) in baptism, by which we are united with Christ, who has made complete satisfaction to the Father for our sins (Romans 6:3-4). In concise, theological terms, the Catholic Church teaches that regeneration, sanctification, and incorporation into the Body of Christ are essential aspects of justification, such that the latter cannot be defined in legal, extrinsic, and individualistic terms alone (source)
The Catholic Catechism writes, “justification conforms us to the righteousness of God”. This is very important here. Catholic theology rejects “legal… terms alone”, and says that justification is the act by which by God infuses the life of Christ in us, thereby allowing us to be righteous in the real sense of the word now.
Now here’s the important part: for the Catholic church, because the merits and righteousness of Christ are literally infused, it is now the role of God’s justified church to cooperate with God’s grace and live out a righteous life, thereby meriting eternal life. Final salvation, for the Catholic church, depends on us living out the righteousness of Christ infused within. This is why the sacraments are so important. The Eucharist is Christ giving us more grace to live out a righteous life. Confession is given to absolve any mortal sin which extinguishes the righteousness of Christ infused in us. Impartation or infusion of Jesus’ righteousness, means that we can now live out the law and merit eternal life.
Now let me be fair: this isn’t salvation by self-merit. In Catholicism, final salvation is not dependent on us living out our own righteousness, but rather the righteousness of Christ infused within. In this way, it is still grace-given righteousness.
However, as a Protestant, I can’t help but notice how the burden is truly on you. As the Catholic Catechism states,
Since the initiative belongs to God in the order of grace, no one can merit the initial grace of forgiveness and justification, at the beginning of conversion. Moved by the Holy Spirit and by charity, we can then merit for ourselves and for others the graces needed for our sanctification, for the increase of grace and charity, and for the attainment of eternal life
The Catechism clarifies, however, saying,
The charity of Christ is the source in us of all our merits before God. Grace, by uniting us to Christ in active love, ensures the supernatural quality of our acts and consequently their merit before God and before men. The saints have always had a lively awareness that their merits were pure grace
While Protestants do have a robust doctrine of sanctification and perseverance, we will not say that growth is tied to our final justification. Justification and sanctification are not bound together in Protestant theology. But for Catholics, justification is a work that God begins freely in us by baptism, but is then merited through sanctification, or cooperation in Christ’s righteousness infused.
As Catholics would say, justification is by faith, but not by faith alone. It is by faith working through love, living out “the divine life” as sons of God.
So, Protestants say justification is imputation. Catholics say that justification is infusion. Small wording change, but to me, this creates the biggest difference in the end.
Want a Catholic’s perspective on the difference? Here is Robert Barron on the Council of Trent, which was created in response to the Protestant Reformation. To get the gist of it, skip to minute 8:45: