In Roman Catholic theology, grace as a substance plays a major role. In fact, the Reformation may be considered across the board (as much as anything else) as a reforming of this wrongheaded view of grace. In some Roman Catholic theology, grace is virtually an impersonal force or energy distinct from God. It gets infused into us in a semi-mechanical way in baptism. Mortal sin causes us to “spring a leak,” so to speak, so that grace runs out of us. Penance patches things up so we can hold infused grace once again. While these analogies are crude, the basic point should be clear. Grace as substance was fundamental to Rome’s deeply distorted soteriology, and the Reformers’ major task was revamping the church’s doctrine of grace (as well as making corresponding changes in church praxis).

The Reformers, at their best, scrapped this patristic and medieval view and understood grace strictly in relational, or covenantal, terms. Sacraments were not “channels” through which the substance of grace flowed into us; rather they were personal encounters with the gracious God himself. They were all about union and communion with Christ, rather than some static, impersonal substance.

Again, an illustration may help: When a husband hugs his wife, he doesn’t pour any substance into her, but he does communicate love and build their relationship. So it is with the sacraments. Through these personal symbols, God graciously interacts with us, forming and nurturing his relationship with us. He expresses his love for us. He communicates Christ — his very person, in the form of the God-man — to us.

Thus, the Word and sacraments work in largely the same way inter-personal human relationships work. We relate to one another through various signs — words, gestures, hugs, handshakes, etc. Word and sacrament are simply the inter-personal means through which the divine — human relationship is initiated and maintained. God deals with us through these symbols. The symbols do not “get in the way” of a closer, more immediate relationship with God; in fact, apart from them, there is no relationship with God at all, any more than two humans can get to know each other apart from exchanging signs and symbols. A God without means of grace is a figment of one’s imagination, just as a “girlfriend” one has never spoken to or taken out on a date is a product of overactive daydreaming.

Sometimes Protestants have fallen into the Romish error of treating grace as a substance, rather than a personal attribute of God. While not altogether objectionable, phrases such as “grace is conferred in the sacrament” (cf. WCF 28.5) tend to imply this. Ordinarily, we might speak of a substance being conferred or conveyed, but not a personal attitude or disposition. Perhaps the time has come for Protestants to more strenuously clean up their sacramental language in order to avoid confusion. Salvation is not so much a new infusion or conferral of anything; it is a matter of a new relationship with God. Grace is not a substance, but a dynamic, covenantal friendship and fellowship with God in and through Jesus Christ.

Rich Lusk, “Some Thoughts on the Means of Grace”