If the idea of two separate classes of Christians, the believers and the disciples, is not found in Scripture, how is such a doctrine defended? The answer is that this doctrine is solely supported by another false doctrine about salvation. That doctrine alleges that the demanding requirements for discipleship are not compatible with the fact that salvation is by grace. Based on that logic, the conclusion is drawn that the requirements for discipleship cannot be requirements for salvation. Thus, being a disciple must be an optional step of commitment for heaven-bound believers who are saved by grace.
The fatal flaw with this theory is that there are scores of scriptures that oppose it. What, for example, could be more clear than what Jesus said near the close of His Sermon on the Mount, after He had enumerated numerous commandments?
Not everyone who says to Me, “Lord, Lord,” will enter the kingdom of heaven; but he who does the will of My Father who is in heaven” (Matt. 7:21).
Clearly, Jesus linked obedience with salvation, here and in many other statements. So how can we reconcile the numerous scriptures like this with the Bible’s affirmation that salvation is by grace? It is quite simple. God, by His amazing grace, is temporarily offering everyone an opportunity to repent, believe, and be born again, empowered to live obediently by the Holy Spirit. So salvation is by grace. Without God’s grace, no one could be saved, because all have sinned. Sinners cannot possibly merit salvation. So they need God’s grace to be saved.
God’s grace is revealed in so many ways in regard to our salvation. It is revealed in Jesus’ dying on the cross, God’s calling us though the gospel, His drawing us to Christ, His convicting us of our sin, His granting us an opportunity to repent, His regenerating us and filling us with His Holy Spirit, His breaking the power of sin over our lives, His empowering us to live in holiness, His discipline of us when we sin, and so on. None of these blessings have we earned. We are saved by grace from start to finish.
According to Scripture, however, salvation is not only “by grace,” but “through faith”: “For by grace you have been saved through faith” (Eph. 2:8a; emphasis added). Both components are necessary, and they are obviously not incompatible. If people are to be saved, both grace and faith are necessary. God extends His grace, and we respond by faith. Genuine faith, of course, results in obedience to God’s commandments. As James wrote in the second chapter of his epistle, faith without works is dead, useless, and cannot save (see Jas. 2:14-26).
The fact is, God’s grace has never offered anyone a license to sin. Rather, God’s grace offers people a temporary opportunity to repent and be born again. After death, there is no more opportunity to repent and be born again, and thus God’s grace is no longer available. So, His saving grace must be temporary.
 Moreover, contrary to those who maintain that we are saved by faith even if we have no works, James says that we cannot be saved by a faith that is alone: “You see that a man is justified by works, and not by faith alone.” True faith is never alone; it is always accompanied by works.