I appreciate the author's emphasis on the grace of God as the means by which salvation is made possible for us by our LORD Jesus Christ and to be experienced. The author, being a versatile theologian, leaves no room for doubt in the efficacy of Christ's substitutionary work on the cross, and in the instant remittance of all its accomplishments in the sinner who heeds the call to believe and be saved.
However, I must say with all due respect that the author finds it difficult to place a clear demarcation between the sovereignty of God and the responsibility of man. He seems to make God responsible for man, as long as he is now in Christ; and that regardless of what the chosen course of his thoughts and actions may be, he cannot be lost. The arguments are quite plausible. But I must underscore the fact that all his assertions about the responsibility of the LORD to keep us, who are in Him, are truths that I rejoice about regularly and often stand in awe of.
Yet, for Christians who are sincere, they will realize that the estate of the believer in Christ is an objective fact, and indeed, no man can make it untrue. But there is a second part to it and that is the subjective aspect. Which is that aspect that deals with what we have actually experienced. If all the scriptures used in this book and even better still, checking the entire testimony of the Word of God, we will see that both parts must always be taken together or else we may find ourselves abusing either the sovereignty of God or the responsibility of man.
Finally, I must state again that I believe everything the bible says. Hence, I believe that "...he is able also to save them to the uttermost that come unto God by him..." (Hebrews 7:25). There cannot be a problem on God's side. However, it is we who must ensure that we continue in Him. "For we are made partakers of Christ, IF we hold the beginning of our confidence stedfast unto the end." (Hebrews 3:14 - emphasis mine). May we all experience all that Christ has obtained for us objectively. AMEN.