Being a born-again Christian means you have become a new creation in Christ. Christianity is not a modification, or an improvement, or a purification of your old life. It is receiving a completely new life, the life of Christ, in exchange for your old sinful life that was executed on the cross of Christ. This is what the Bible means by the experience of conversion or regeneration, which we covered in our last study.
The moment you experienced the new birth, you passed from death to life, or from condemnation of the law to justification unto life. This is the beginning of the Christian walk. Now that you have the life of Christ, through the indwelling of the Holy Spirit, your goal in life must be to manifest that life, so that all may see “Christ in you.”
The work of subduing the sinful desires of the flesh and reproducing the holy and righteous life of Christ in you is the work of the Holy Spirit. This work is the process of sanctification. And while this experience of sanctification does not contribute one iota towards your title to heaven, it witnesses the salvation you already have in Christ through justification by faith. Hence, sanctification, which is the fruit of the Spirit, is witnessing true justification by faith or the power of the gospel.
But for this to happen, you must learn to walk in the Spirit. In Adam, all you were capable of was to walk in the flesh, satisfying the drives of the sinful nature. But now, as a born-again Christian, you are able to walk in the Spirit as Christ Himself did when He was on this earth. This is what this lesson is all about — the experience of walking in the Spirit.