Clark's view of saving faith is not exactly what it would appear to be at first. For Clark knowledge and a changed mind (repentance) results in actual change in the person's life, although, as my quote shows, Clark had to face the fact that no amount of knowledge or obedience could distinguish between true assurance and false assurance. In my opinion, Clark never fully solved the "apparent" contradiction between the absolute demands of God's moral law and the "apparent" antinomianism of justification by faith alone. Mike Horton calls the distinction between justification and sanctification a "paradox." Clark said that only justification is alone. Salvation would include the whole ordo salutis or "order of salvation." In time and from the human perspective Clark said that salvation includes: unconditional election, regeneration, effectual call, faith, conversion, justification, repentance, adoption, progressive sanctification, perseverance o the saints, and glorification. In other words, Clark includes the whole system in his view of salvation, not just justification. From that perspective he would say that sanctification is necessary for assurance of salvation. But the apparent contradiction, as Clark admitted, is that you can never know enough or obey enough to distinguish between true assurance and false assurance. I wish he had worked on this more. I'm thinking through this and plan to write a blog article on it in the future. It would seem to me that the bottom line--even for Clark--is that ultimately salvation MUST be rooted in justification by faith alone. Seen from that point of view, then, sanctification is only an outward sign before the church, not a basis for for salvation. God does not grade on a curve. Either you are sinless or you are not. And since everyone is a sinner, salvation itself must be by faith alone (Romans 3:23; Romans 4:1-8). Everything else is merely a fruit produced by the gifts of regeneration and faith. Even sanctification is not rooted in "free will". That would mean that we sanctify ourselves by our own efforts. Sanctification is itself a gift since it is God who works in us (Philippians 2:13).
Moral agency is not the same thing as libertarian free will or a choice between two equally valid choices. Choosing evil is never a valid choice. Good and evil are not equal choices. While we are fully accountable and responsible to obey God's moral law and we are without excuse when we break God's law, it is also true that whatever happens is ordained of God. That would include even our moral failures. God often humbles us by causing us to sin so that we can see the truth of the proposition that Jesus made:
I am the vine, ye are the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing. (John 15:5 KJV)
Everything else results in human pride. The Pharisees are a great example of that. You can see that in some of the advocates of Clark's theology because many of them read Clark out of context, highlighting what he said in regards to conversion and sanctification but ignoring what he said about saving faith and justification by faith alone. The whole system of theology has to be taken from the Bible, not just the individual propositions taken out of context. That would mean that Monty Collier is off when he emphasizes only justification by faith alone while ignoring the implications of sanctification as a process. And it would mean that Sean Gerety is wrong when he asserts that sanctification is synergistic when it is clear that Clark rejected the idea that sanctification is rooted in the Arminian doctrine of "libertarian" free will. Clark's view is more nuanced than that. And, in my opinion, Clark leaves a few loose ends for us to clear up. He was not perfect and even Clark could make mistakes in logic. I am certainly no expert in philosophy or logic. Clark was a genius in that regard. But it seems to me that if I had to choose I would much rather say that salvation is founded solely on justification by faith alone and work from there. Without that doctrine we wind up right back in the Papist confusion of justification with sanctification. Yet, true faith must result in some sort of change in our thinking and thus in the way we live. Repentance is not being sorry for sin. Repentance is "metanoia," literally a changed mind, a change in the way we think (Romans 12:1-2).
The spirit is willing but the flesh is weak (Matthew 26:41). Romans 7 was not written prior to Paul's conversion but afterwards! The sinful mind is at enmity with God (Romans 8:7). Basically, it is only our faith that makes us stand (Romans 5:1-2) and it is faith that saves us from the condemnation of the law (Romans 8:1-2). The chapter divisions in Romans, by the way, are not in the original Greek manuscripts. The punctuation, versification, and chapter divisions are all traditions added later by the church and other scholars.
Clark's comments on salvation in his lecture on sanctification show that he believed that the habits of a regenerated person change from the moment of conversion. He rejected the Wesleyan perfectionism which wrongly interpreted 1 John 5:18 because such a view would contradict 1 John 1:8-10. Sin is any lack of conformity to God's moral law, not just a willful disobedience to a known moral law. Sins committed in ignorance are still sinful. (Cf. What Presbyterians Believe: Sanctification).
That is not to say that the elect do not fall into grievous sins and suffer temporal punishments. They do. The Old Testament saints prove this out well enough, as you pointed out in your e-mail earlier. The Calvinist doctrine of eternal security is called the "perseverance of the saints" because it is not the same as the "once saved always saved" view of the Baptists. Walking an aisle and being dunked does not save anyone. That is called "easy believism." On the other hand, no amount of obedience can generate assurance of salvation. Clark said that obedience contributes to assurance but ultimately it must be justification by faith alone that gives us true assurance. Perseverance is a lifelong struggle and there are many failures along the way. Even though the elect can and do often lose their assurance of salvation, they can never lose salvation itself. (Jude 1:24-25).
For Clark, the Christian needs to learn all the Scriptures from Genesis to Revelation (1 Corinthians 2:16). For Clark the Gospel is the whole Bible, not just the inductive understanding of the bits and pieces. The law/Gospel distinction is certainly in the Bible. The law and Gospel are embedded in the Scriptures throughout. But that does not mean we get to pick and choose which Scriptures to preach and teach. A Gospel preacher must preach the whole counsel of God! (Acts 20:27).