I have been reading an unbelievable book entitled The Gospel Mystery of Sanctification: Growing in Holiness by Living in Union with Christ by Walter Marshall. The back of the book reads:

The Gospel Mystery of Sanctification by Walter Marshall, first published in 1692, is one of the classic works of Christian spirituality. It is a deep and rich biblical study of sanctification—how Christians grow in holiness and become more like Jesus. In a day when Christians are very prone to pursue self-help methods to grow in obedience to Christ, Walter Marshall lays out the biblical way of growth: Obedience comes as Christians live by grace, in union with Christ by faith. Growth comes, as Paul says in Galatians 2:20, through "Christ living in me."

I have been stunned by the gospel-centeredness of this book. I have been even more stunned that I have never heard of this book before, nor have I spoken with anyone else who has heard of this book either. Shocking for a book that Dr. John Murray, the late professor of systematic theology at Westminster Seminary in Philadelphia, said that this book was the most important book on sanctification that had ever been written. The introduction of the book, written by Bruce McRae, states:

The great theme of Walter Marshall's book is that Christians grow in obedience by the power of the gospel, not by their own strength. Christians are in union with Christ, and their Christian growth flows from this union, not from their own efforts. The gospel is essential for growth in holiness…The gospel says that through faith in Christ, you are completely forgiven of all your sins. Then, having been forgiven, you are called to sanctification by faith in Christ as well. Sanctification is the lifelong process of being conformed to the image of Jesus Christ. All Christians agree on this point: Christians are called to pursue godly, holy living. On this point there is simply no debate. However, confusion sets in as soon as the question is asked, "How do Christians become holy? Where does the power for godly living come from?

This book answers the questions, "How do Christians become holy?" and "Where does the power for godly living come from?" At times the book can become a bit redundant. You may feel as if you are reading the same thing over and over again. You are. This is the wisdom of the Puritans. This is their understanding and putting into practice Martin Luther's statement that the gospel must be beaten into our heads continually.

The book is structured around Marshall's fourteen principles of holiness. Simply reading these fourteen principles allows you to see the nature of gospel sanctification:

1. 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.
2. You have to receive certain qualifications 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.
3. 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.
4. 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 fruitfulness, 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.
5. 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.
6. 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 true obedience, you will never succeed.
7. 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.
8. 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.
9. In order to sincerely keep the law of God, you must first receive the comfort of the Gospel.
10. 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 this 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.
11. 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.
12. In order to obey the law of God, earnestly live by your most holy life. Do not walk according to your old nature, and do not 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.
13. Now the Holy Spirit has renewed you, God calls you to live a holy life. To live this obedient 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 the means of grace he has given you in his Word.
14. I have been telling you up to this point that you must seek to live a holy life by believing in Christ, and by 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.

The book itself is fourteen chapters long, each chaptered being an exposition of the above principles. The edition of the book that I have been referring to and quoting from is a new edition of the book that has been put into modern English by Bruce McRae who teaches practical theology at Reformed Theological Seminary. McRae was first introduced to this book by Jack Miller, a name synonymous with gospel-centeredness, but had a difficult time locating a copy of it. He finally found an edition that was printed in the mid 1800's and was not allowed to leave the theological library in which it resided. It took quite some work before he was able to find a copy that he could actually use. McRae tells of his own use of the book as a pastor:

I first began to use Walter Marshall's book when I served as a local church pastor. The key issue I faced in trying to disciple Christians for holiness was this: they constantly felt defeated and discouraged in their Christian lives because they tried and failed to change so many times! Walter Marshall addressed this issue better than any other book that I had ever read. This is largely because Walter Marshall was a pastor himself, and he continually observed Christians all around him struggling—and failing—to grown in holiness. Because of the difficulty of the original language version, I found it necessary to rewrite the book in modern English, so that people could read it, understand it, and profit from it.

I owe a great debt to Bruce McRae for taking the time to make this book once again accessible to a generation of Christians desperately in need of gospel-centered holiness—gospel sanctification. This is both a personal as well as pastoral debt. I am indebted personally because as a pastor I do not have it all together. I face no less the struggles of the people that I love and am called to shepherd. Some days I blow it and need to be reminded that my sanctification is not accomplished through being a pastor, but through grace in the gospel. I am indebted pastorally because the holiness of my people is accomplished through the gospel in the same way that the holiness of their pastor is accomplished through the gospel.

I pray that pastors and church members will spend long hours lost in the pages of this book. May an old voice from the past remind us, as Marshall says, "the key error of the Christian life is that people think that even though they have been justified by a righteousness produced totally by Christ, they must be sanctified by a holiness produced totally by themselves." How true is that in your life? I find that to be the consensus belief among so many Christians.

McRae says, "The message of this book will bring freedom and encouragement to many Christians who are struggling, and failing, in their Christian growth." This book does exactly that. Thank God for gospel-centered men who remind us.