Marshall’s thesis is that sanctification is not something that can be realized in the Christian life by our own power and struggle to grow in holiness but rather that it comes from the union that we have with Christ as we fellowship with him and with his holiness. By faith we receive all of the blessings of the gospel; not just justification but also sanctification. Marshall also goes on to then detail how we can progress in holiness from knowing that we are secure before God because of justification by grace through faith in Christ by living out what is already ours in him.
The whole book is certainly written with a pastor’s heart. Early in his life, Marshall was distressed about the state of his soul for many years and could not find peace as he struggled with his guilty conscience. He felt that God was displeased and angry with him. Eventually he spoke with the great Puritan pastor, Thomas Goodwin, confessing several of the sins that weighed on him most heavily. Goodwin replied, “You have forgotten to mention the greatest sin of all: the sin of unbelief. You do not believe in the Lord Jesus Christ to forgive your sins and to sanctify your nature.” This reply changed Marshall’s whole approach to salvation as he realized that it is only in Christ that we are justified and then also sanctified and he spent the rest of his life, including this book, proclaiming that gospel. The hymn writer William Cowper wrote in a letter to his cousin:
Marshall is an old acquaintance of mine. I have both read him and heard him read with pleasure and edification. The doctrines he maintains are, under the influence of the Divine Spirit, the very life of my soul, and the soul of all my happiness; that Jesus is a present Savior from the guilt of sin by his most precious blood, and from the power of it by his Spirit; that corrupt and wretched in ourselves, in him, and in him only, we are complete. . . . I never met with a man who understood the plan of salvation better or was more happy in explaining it. [Cited in McRae’s introduction]Here are the principles that form the basis of Marshall’s chapters:
- God in his law calls you to live a holy and righteous life. In order to do this, you first have to learn the only possible way you can live a holy life.
- You have to receive certain qualification to keep the law of God. There are four qualifications for living a godly life which you must receive from God: 1) Your heart has to be freely willing to live a godly life, 2) You have to be assured that you are forgiven and reconciled to God, 3) You have to be sure of a happy, eternal future with the Lord, and 4) You have to have sufficient strength both to will and to do what God calls you to do.
- You receive the qualifications to enable you to keep the law of God out of the fullness of Christ, through fellowship with him. In order to have this fellowship, you must be in union with him. You must be in Christ, and Christ himself must be in you.
- The Gospel is the way the Holy Spirit brings you into union with Christ, and into fellowship with him and his holiness. Through the gospel, Christ enters your heart and gives you faith. Faith is the way you actually receive Christ himself, and all his fullness, into your heart. Even this faith is a grace of the Holy Spirit. When you have faith, you believe the gospel with all your heart. When you have faith, you believe in Christ, as he is revealed and freely promised to you in the gospel, for all his salvation.
- You cannot live a holy life, no matter how hard you try, if you still have your old nature. In order to live a holy life, you have to receive, by faith, a new heart and a new nature, through your union and fellowship with Christ.
- If you try to obey the commands of Christ in order to earn your salvation, and to gain assurance of your salvation, you are seeking salvation by the works of the law. You are not seeking your salvation through faith in Christ, as he is revealed in the gospel. If you try to earn your salvation by your true obedience, you will never succeed.
- Do not think that your heart and life have to be changed from sin to holiness in any measure before you are allowed to trust in Christ for salvation.
- Make sure that you seek holiness of heart and life in its proper time. You can only live a holy life after you have come into union with Christ, have been justified, and have received the Holy Spirit. Once you have received these blessings, seek holiness by faith with all your might. It is a crucial part of your salvation.
- In order to sincerely keep the law of God, you must first receive the comfort of the Gospel.
- If you are going to obey the law out of the comfort of the Gospel, you must have complete assurance of your salvation. You obtain assurance by believing and receiving Christ into your heart. Therefore, confidently believe in Christ without delay. Be assured that when you believe in Christ, God will freely give you a personal relationship with Christ, just as he has promised.
- Believe in Christ without delay! Then, continue to build up your faith. When you do this, you will build your relationship with Christ more and more. You will also be empowered to live a holy life.
- In order to obey the law of God, earnestly live by your most holy faith. Do not walk according to your old nature, and do not put into practice anything that belongs to your old nature. Walk only according to the new nature you received by faith, and live the lifestyle of your new nature. This is the only way to live a holy and righteous life – as much as is possible in this present life.
- Now that the Holy Spirit has renewed you, God calls you to live a holy life. To live this obedience life, you must continue to believe in Christ and walk in him by faith. To live this life of faith, God calls you to diligently use all of the means of grace he has given you in his Word.
- I have been telling you up to this point that you must seek to live a holy life by believing in Christ, and be walking in him by faith. If you are going to do this, you must understand why living by faith in Christ is so important and beneficial to your soul.
This is probably one of the most helpful books that I’ve ever read. I cannot recommend it highly enough for Marshall’s detailed treatment of sanctification and how it entirely stems from our Spirit-wrought union with Christ in being brought into conformity with his death and resurrection as our death to sin and being raised to righteousness. Marshall’s careful interaction with related and important subjects such as justification, assurance of salvation, glorification, and the means of progressing in the Christian life are invaluable. This should go on my list of books that every Christian should read.