Salvation as used in this context includes our justification (the declaration of righteousness), sanctification (personal holiness), and glorification (complete conformity to the image of Christ). No one has been more vocal in making this claim than the Baptist theologian John Piper but he has allies within the P&R world echoing his claim but this claim has been refuted at length.
It has become fashionable among some who identify as confessionally Reformed and among so-called Reformedish (i.e., Baptists who identify with aspects of Reformed theology) types to claim that the Reformed doctrine of salvation hold that there two stages to salvation: initial and final. Further, they claim, Reformed doctrine is that our so-called initial salvation is by grace alone (sola gratia), through faith alone (sola fide) but that our alleged final salvation is through works. Salvation as used in this context includes our justification (the declaration of righteousness), sanctification (personal holiness), and glorification (complete conformity to the image of Christ). No one has been more vocal in making this claim than the Baptist theologian John Piper but he has allies within the P&R world echoing his claim but this claim has been refuted at length. See the resources linked below.
There Is A Mainstream Of Reformed Theology
One of the tactics used by the P&R advocates of this view is to emphasize the diversity of views held by Reformed theologians in the 16th and 17th centuries (hereafter the classical period of Reformed theology). Typically, we see them making appeals to theologians who were historically important but whose views were controversial in their own time (e.g., Amyrault, Davenant) and whose views were not adopted by the Reformed Churches. As a matter of history it is true that there were outliers and marginal figures but it is also true that those outliers do not define Reformed theology, piety, and practice. The Word of God as confessed by the churches in official ecclesiastical summaries define Reformed theology.
Catechisms Are Not Mere Systems
One of the mistakes made by those who kibitz in Reformed theology (i.e., the Reformedish and by the P&R advocates of final salvation by works is that they confuse confessions and catechisms for mini-systematic theologies. These are two distinct kinds of documents. A system or a treatise published by an individual is just that. It does not define Reformed theology. An ecclesiastical confession or catechism has a different status. It is a churchly document. It has secondary but genuine authority. No one can be prosecuted in the assemblies of a confessional Reformed church for dissenting from Hodge’s Systematic Theology but one can be convicted for contradicting the Word of God as confessed in the Heidelberg Catechism, the Belgic Confession, or the Canons of Dort.
The confessions of the church are not mere private opinions. They are ecclesiastical dogma. Contra Rome, that are corrigible, however. They are always subject to the Word of God. Indeed, in the classical period Protestants not only revised confessions, they wrote new ones regularly. One of the oddities of the Modern period has been the reluctance to do in our time what our forebears did in theirs: confess the faith anew in response to new challenges. I argued this case in Recovering the Reformed Confession. More recently Modern Reformation magazine invited me to re-state the case.
The Heidelberg Catechism
One of the foundational ecclesiastical documents in the Reformed tradition is the Heidelberg Catechism. It was published in 1563 by order of Frederick III, Elector Palatinate, in order to help consolidate what had been a turbulent religious situation in the Palatinate. Authored primarily by Zacharias Ursinus, who also lectured on it, the catechism synthesized much of theology, piety, and practice of the Reformation (and especially the Reformed reformation) that preceded it.
In the Heidelberger, the Reformed Church of the Palatinate confessed unambiguously the doctrine of salvation (as defined) by grace alone, through faith alone. They did so (as we do today), against those (Rome and the Anabaptists) who taught and confessed salvation by grace and cooperation with grace, a two-stage doctrine of salvation, or final salvation through works. The Reformed Churches saw that doctrine as a flat contradiction of the Word of God.
The catechism speaks explicitly to the doctrine of salvation right at the outset of the catechism. Our comfort is not only that we are justified by grace alone, through faith alone on the basis of the imputed righteousness of Christ alone but also that we are saved by grace alone, through faith alone:
Q. 1. What is your only comfort in life and death?
A. That I with body and soul, both in life and death, am not my own, but belong unto my faithful Saviour Jesus Christ; who, with his precious blood, has fully satisfied for all my sins, and delivered me from all the power of the devil; and so preserves me that without the will of my heavenly Father, not a hair can fall from my head; yea, that all things must work together for my salvation, and therefore, by his Holy Spirit, He also assures me of eternal life, and makes me sincerely willing and ready, henceforth, to live unto him.
Were it true that ther are two stages of salvation and that final salvation is through works, as some claim, the basis of our assurance is destroyed. How many works? Of what quality are necessary to qualify one to be finally saved? The proponents of final salvation through works bristle at this question. They say, “God works them in us.” Their response shows that they do not understand the Reformation. There were plenty of medieval theologians who taught that same thing and the Protestants rejected it too. Further, their response does not answer the question. It also ignore the reality of means and instruments. If our good works are the instrument of our final salvation and if I am not a stock and block (a calumny that the Reformed denied in just those terms), then my part in obedience is necessarily a part of the instrument of my salvation.
The Reformed Churches salvation is utterly the gift of God received through faith alone.
Q. 21. What is true faith?
A. True faith is not only a certain knowledge, whereby I hold for truth all that God has revealed to us in his word, but also an assured confidence, which the Holy Spirit works by the gospel in my heart; that not only to others, but to me also, forgiveness of sin, everlasting righteousness and salvation, are freely given by God, merely of grace, only for the sake of Christ’s merits.