When it comes to being right with God – being declared righteous by God and accepted by him – all our works are completely excluded. Or, as the Bible says, we are not justified by works, but by faith in Christ (Hab. 2:4, Rom. 3:28, 10:10, etc). This is the meaning behind these solas: faith alone, grace alone, Christ alone, to God’s glory alone. Geerhardus Vos explains justification apart from works in volume three of his dogmatics:
Not only the works that we do in our own strength, or that we do before regeneration, or that we do without the merits of Christ, but all [our] works, of whatever sort, are excluded from justification.
This is so repetitively certain in Scripture that proof is almost superfluous. Galatians 2:16 reads, “… nevertheless, knowing that a man is not justified by law-works [ἐξ ἔργων νόμου].” In no way is the reference here to works prescribed by one or another specific law, because the article is missing. All law-work as such is excluded from justification. According to Paul, faith and works form an absolute contrast in the matter of justification (Rom 11:6).
This must be maintained against the Roman Catholic teaching about the instrumentality of works in justification, as well as against Pelagians, Rationalists, and Remonstrants. The first two mentioned, the Pelagians and Rationalists, maintain that Scripture excludes only the works of the Jewish law, that is, the ceremonial law, but that the moral law certainly has to be observed by us for justification.
The last, the Remonstrants [the 17th century Arminian group], go one step further, and in place of the moral law in all its severity put a lighter form, the law of the obedience of faith. They speak of a fides obsequiosa [submissive faith] and of an obedientia evangelica [evangelical obedience], which, while in itself not perfect, is accepted by God as perfect.
Vos also summarizes the “causes” of justification. Notice the work of the triune God in justification:
The effective cause (causa efficiens) of justification is God, more accurately God the Father, and still more accurately His grace and righteousness. The meritorious cause is the obedience of Christ the Mediator (causa meritoria). The instrumental cause (causa instrumentalis) is faith worked in the heart through the Holy Spirit and then put into action. The final cause (causa finalis) is the glorification of God regarding all His virtues related to justification.
Of course we want God to receive all the glory in everything – especially our redemption. When we submit to Scripture and acknowledge that God justifies sinners because of Christ’s imputed righteousness received by faith alone, we give God all the glory. When we admit that even our faith is a gift of God the Holy Spirit, we give God all the glory.
Not to us, O Lord, not to us,
But to Your name give glory!
(Ps. 115:1 NASB)
Geerhardus Vos, Reformed Dogmatics, ed. Richard B. Gaffin, trans. Annemie Godbehere et al., vol. 4 (Bellingham, WA: Lexham Press, 2012–2014), 143, 151–152.