I disagree with the author´s premise of considering the natural man to be involved with Christ, as if one must not deny their self. But when one is truly born again, they will no more seek their own will, but the will of the Father, and will no longer look at things as they naturally think is the best way, or what they naturally think is the closest to right and wrong; there will be no more guess work with them, for they will evaluate, determine, and conclude all matters by the will of God, which is the Word of God through the Spirit of Truth, and not by any natural inclinations. But please do not misunderstand, I am not at all suggesting that the Christian is as a robot, rather they are unmovable in their devotion and reliance in Christ. Besides this, we must follow Christ, not beside Him, or in front of Him, but behind Him.
A lot of what the author is subtly near to is the new age way of thinking, who justify themselves before men, but as for the professing Christian, let them hold to God´s Word alone, for we need not that any man teaches us, if it be so that we have the Holy Spirit in us, and let us rather learn not to think beyond that which is written.
The grace of our Lord Jesus Christ be with you.

References:
John.5:30
Romans.8:5-9
Luke.16:15
I Corinthians.4:6
I John.2:27