There is a tendency in evangelicalism, in post-Reformation theology, to emphasize a certain quality of faith that is reminiscent of Roman Catholic doctrine. In other words, faith is your expression.
It is not an issue like Arminianism, which suggests that faith is your doing with a semi-Pelagian notion of free will. Within the semi-Pelagian and Arminian view, you are saved by your free will in cooperation with God’s sovereignty. For the Synod of Dort, that was just as bad as saying you are saved by the sacramental treadmill of medieval Roman Catholicism.
There arose a tendency in evangelicalism to say that you are saved by faith—but what kind of faith? How much faith? Or, similarly, that repentance is necessary for salvation—but how much repentance? What quality of repentance? It becomes something that you do in addition to faith. So, the Westminster Divines in the middle of the seventeenth century made it clear that we are saved by faith. However, faith is not just the instrument through which the grace of God operates, because it cannot operate apart from faith. The gospel does not operate over our heads; it does involve our responsive faith and repentance, which are gifts from God.
In Calvinistic circles, particularly in Holland and Scotland, there arose a tendency to say that if you express assurance of your salvation before your faith has matured and before you have sensed the evil of sin and the wretchedness of your heart, you are an immature Christian because the mature Christian waits for assurance. In other words, the ground of their assurance is the quality of their faith and repentance, which is a subtle form of bringing works into salvation again.