The apostle Paul exhorts the believer to wage war on sin. He writes, "So then, brethren, we are under obligation, not to the flesh, to live according to the flesh— for if you are living according to the flesh, you must die; but if by the Spirit you are putting to death the deeds of the body, you will live. For all who are being led by the Spirit of God, these are sons of God" (Romans 8:12-14 NASB).
Jared Wilson, in his excellent post "Spare No Sin You Find," presents this message well. He writes, "We don’t graduate from the gospel. We hold true to it. And it alone propels us out and empowers us to press on. Grace-driven effort flows from the joys and wonders of worship that flow from beholding the amazing gospel of God’s grace.
Were this true in you, the sin in you would become your enemy. Do you profess Christ? Have you received Christ? Then, 'Don’t just avoid sin; hate it' (Ed Welch). Be as intentional with your sin as Christ was. Carrying the banner of the gospel, which declares Christ’s conquering of sin and death, make bloodthirsty war with the sin in you. Watch for it, search it out, assassinate it with the word of God. Arm yourself with Spiritual armor, put on Christ, and spare no sin you find. Kill it, even as you trust the Spirit is killing it on your behalf. Because he is. And if he is, you should be too.
You won’t drift into holiness. The Spirit will take you there. But God uses means to achieve his ends, and his earthly means of Spiritually sanctifying you is your pursuit of the righteousness of Christ. That we are 'being transformed' is a promise; that we should 'be transformed' is a command (2 Cor. 3:18; Rom. 12:2). This Spiritual tension causes Walter Marshall to affirm in The Gospel Mystery of Sanctification, his classic work affirming that grace is not only the grounds of our justification but our sanctification as well, that the reader must 'endeavour diligently to make right use of all means appointed in the word of God, for the obtaining and practicing holiness.'”