All Reformed Protestants deny that sanctification will be perfect or complete in this life. Thus even “good works” are performed by those who still must combat abiding sin.
Believers, then, cannot be perfectly good. Nor can their works be perfectly good. But does this mean that they cannot be truly good? In other words, are they actually sinful actions in and of themselves because they do not proceed from a heart that is wholly pure?
The seventeenth-century theologian Francis Turretin, in Institutes of Elenctic Theology XVII.4.Xff., says no. Or, to put it another way, he argues that the “good works” of believers (and only of believers) are truly good, while making the appropriate qualifications (there is even a way of speaking of them as “sins” accidentally with respect to mode, because they are accompanied by defects and blemishes). Turretin has several reasons for thinking this. He begins as follows:
X. That the works of believers are truly good is proved: (1) because they are not performed only with the general concourse of God, but by a special motion and impulse of the Holy Spirit, who dwells in the hearts of believers and excites them to good works. Hence these works are usually ascribed to him as the primary cause (Ezk. 36:27; Gal. 5:22; Rom. 8:9, 10; Phil. 1:6; 2:13). Nor are they done only with the Holy Spirit exciting and impelling, but also with the qualities of infused grace mediating (which overcome the order of nature). Hence Paul ascribes all his works to the grace of God (1 Cor. 15:10) and Christ asserts that we can do nothing without him (Jn. 15:5). Now what is produced by the Spirit and the grace of Christ is not able not to be truly good. Nor does the flesh, which still remains in us, hinder this because its presence can indeed take away the perfection of sanctification, but not its truth. 1
Turretin here argues that believers’ works are good firstly because their primary cause is the Holy Spirit. In addition to the “impulsion” of the Holy Spirit, believers have grace that has been poured into them to which their works should be attributed. Turretin utilizes the category of “infused grace” (gratia infusa), as opposed to “imputed grace” (gratia imputata), to speak of sanctification, just as Westminster Larger Catechism Q/A 77 does. The “qualities” of this grace lead believers to acting in a new way; when Turretin says that the qualities of this grace “overcome the order of nature (naturae ordo),” he must mean nature as fallen, for nature as created is good; it is on fallen nature that grace does its restorative work.
But notice what this means: if such works proceed from the Holy Spirit and God’s grace, they must be good, because God is good. If something is produced by the Holy Spirit and the grace of God, it is, as Turretin says, “not able not to be truly good.”
This is so even though believers still must fight with sin. Sanctification, in other words, is not an all-or-nothing proposition. There is a difference between perfect sanctification and true sanctification. It is God who is at work in his people, and thus the latter can exist even if the former, in this life, cannot. And again, this is so because God himself is the “first (or ‘chief,’ or ‘principal’) cause” (primaria causa) of all good that believers do. And because he is this first cause, what he originates is truly good.
In the next section, Turretin discusses how it is that one can say that such works are pleasing to God.