Paul frequently describes the Christian life in very physical terms, far beyond merely “walking in the Spirit”. Paul describes the Christian life as running a race in 1 Corinthians 9:24-26, where he also uses the imagery of boxing. The author of Hebrews says “let us also lay aside every encumbrance and the sin which so easily entangles us, and let us run with endurance the race that is set before us” (Heb. 12:1b). In Ephesians Paul plainly states that there is a struggle that requires us to use strength given by God, that there is genuine warfare against the devil and his demonic forces (Eph. 6:10-13). Time and again the Scriptures paint a picture of effort, not earning. Willem Van Gemeren writes: “Paul defines true wisdom (or godliness) as the pursuit of the triune God. He speaks of wisdom as a walking with God the Father, the Son, and the Holy Spirit. He calls upon Christians to walk worthy of God (1 Thess. 2:12; 4:1-8), to be filled with the fullness of God (Eph. 3:19), to put on the Lord Jesus Christ (Rom. 13:11-14), to live in Jesus Christ (Col. 2:6-7), and to walk in the Spirit (Rom. 8:4-11). Paul contrasts the life in the Spirit with the carnality of the world (1 Cor. 3:1-4; 10:1-10; Gal. 5:16-21). The newness of life is theocentric and produces nothing less than a godly way of life, as evidenced by the fruit of the Spirit (Rom. 6:22; Eph. 5:1-2; Gal. 5:22-23; Col. 1:9-10)” The “newness” of life produces evidence that demonstrates the proper functioning of the power dwelling within.
What separates mere effort from the process of sanctification is the power behind it. The Bible states that the best works man can offer are like filthy tatters of cloth before God (Isa. 64:6), so clearly the best efforts of man will not elevate him in the process of Christ-likeness. John M. Frame points out that many secular writers, including the likes of Aristotle, have highlighted the great importance of inner righteousness. While they struggle with the need for such inner character, “they have not succeeded in showing what constitutes virtue or how such virtue may be attained. This insight is based on God’s lordship attribute of presence, ‘for it is God who works in you, both to will and to work for His good pleasure’ (Phil. 2:13). Without inward regeneration and sanctification, our best works are hypocritical.”
Frame summarizes the struggle with works and grace in the context of sanctification this way: “In justification, our works play no role. God accepts us as righteous solely on the basis of Christ’s atonement. In sanctification, God’s grace is equally pervasive, but there is a role for our efforts. All our goodness comes from God, but it is still important for us to take up arms against Satan and do what is right…So Protestants have maintained that justification is ‘by faith alone.’ Sanctification is also by faith, but not by faith alone…It is not by faith alone, for human effort is necessary to achieve it. Of course, it is God’s grace that gives us the ability to put in that effort. But human effort is necessary for sanctification in a way that is not necessary for justification. Even though sanctification is not by faith alone, it is certainly by faith. In our quest for holiness, we must above all trust God.”