Even within the Reformed churches and within broader evangelicalism influenced by some aspects of Reformed theology (but not themselves Reformed nor members of Reformed churches) many have been tempted to modify Reformed theology in similar ways. E.g., it is popularly taught in some quarters that sinners are initially justified (declared righteous with God) sola gratia, sola fide but they are said to be finally justified and saved “through works.” This is their language. For more on this error see the resources below.
The single most frequent way to corrupt the doctrine of perseverance has been to turn it into a covenant of works. This happens regularly outside the Reformed churches. E.g., the Romanists teach that, in baptism, sins are graciously washed away, initial justification is given, and regeneration is imparted. From there, it is essential for the Christian to exercise his free choice, to do his part, and to cooperate sufficiently with grace in order to become sufficiently sanctified so as to be finally justified. The Protestant churches rejected this system because it confuses the law and the gospel, because it denies the grace of God, and because it denies the finished work of Christ for sinners. It make Christ, as we say in the Belgic Confession (art. 22), “but half a Savior.” Orthodox Lutheranism verged back in this direction by agreeing with the (Romanist) Council of Trent that grace is resistible, that baptism necessarily regenerates (unless one places an obstacle in its way) but that one can resist grace so as to fall away. Thus, implicitly, cooperation with grace (in the form of not resisting) becomes of the essence of remaining in a state of grace. One will not hear Lutherans saying this, of course. Such a doctrine is a departure from what Luther taught in his catechisms (1529) and in On the Bondage of the Will (1525). The Reformed preserved Luther’s doctrine of unconditional grace and salvation and defended it in colloquies (formal discussions) with the Lutherans in the 16th century, e.g., the Colloquy of Montbeilard (1580). On this see Jill Raitt’s excellent work. The so-called “evangelical Arminians” (e.g., Wesleyans) also departed from the Reformation doctrine of perseverance so that it becomes, in their system, what the Reformed called a covenant of works. The believer must do his part in order to remain in a state of grace.
At the Synod of Dort the Reformed churches reaffirmed that Christians persevere and are preserved sola gratia, by grace alone, sola fide, through faith alone. Even within the Reformed churches and within broader evangelicalism influenced by some aspects of Reformed theology (but not themselves Reformed nor members of Reformed churches) many have been tempted to modify Reformed theology in similar ways. E.g., it is popularly taught in some quarters that sinners are initially justified (declared righteous with God) sola gratia, sola fide but they are said to be finally justified and saved “through works.” This is their language. For more on this error see the resources below.
The first indicator that such teaching is a departure from the theology and piety of the Reformation is distinction between “initial” and “final” justification (or salvation). This is not a biblical way of speaking nor is it a Protestant way of speaking. It is, however, a Romanist way of speaking. Scripture says, “Therefore, having been justified by faith, we have peace with God through our Lord Jesus Christ” (Rom 5:1; NASB). Scripture says “For by grace you have been saved through faith; and that not of yourselves, it is the gift of God” (Eph 2:8; NASB). The Holy Spirit has said nothing in Holy Scripture about an initial justification and nothing about an initial salvation as distinct from a final justification or final salvation.
The older Reformed theologians did distinguish between gaining title to salvation and taking possession of it but both were said to be by grace alone, through faith alone. Good works were consistently said to be fruit and evidence of salvation not the instrument of salvation. Faith is the alone instrument of justification, sanctification, and glorification (the three aspects of salvation).
The confession of the Reformed churches is clear about this and no particular confession is more clear about the graciousness of perseverance and salvation than the Canons of the Synod of Dort.
So it is not by their own merits or strength but by God’s undeserved mercy that they neither forfeit faith and grace totally nor remain in their downfalls to the end and are lost. With respect to themselves this not only easily could happen, but also undoubtedly would happen; but with respect to God it cannot possibly happen, since his plan cannot be changed, his promise cannot fail, the calling according to his purpose cannot be revoked, the merit of Christ as well as his interceding and preserving cannot be nullified, and the sealing of the Holy Spirit can neither be invalidated nor wiped out (Canons of Dort, 5.8).
In the previous section (articles 5–7) we saw the Pauline/Augustinian/Reformed realism about reality of sin in Christians in this life (as distinct from the Pelagian/Wesleyan doctrine of entire perfection). Christians sin, sometimes grievously. Only because God restrains the consequences of our sin (mercy) and only because he is unconditionally (as far as we are concerned—Christ met the conditions of the covenant of works for us to make possible for us to receive the benefits of the covenant of grace) favorable (gracious) toward us are we preserved and thus persevere.