I once viewed a scene in a made-for-television movie depicting a young bookstore owner asking her elderly employee, “If you had your life to live over what would you do differently?” The elderly employee answered, “I would follow my heart more.” Good advice or bad advice? Both! Good advice for the Christian; bad advice for the non-Christian.

The purpose of this book is to teach you that living in the Spirit is as simple as following your heart; that is, if you are a Christian—one whose heart has been invaded by the presence of God in the person of the Holy Spirit. If you are not a believer in the Lord Jesus Christ, then following your heart would be a tragic mistake, as the Bible warns in Proverbs 14:12, “There is a way which seemeth right unto a man, but the end thereof are the ways of death.” The unregenerate heart, described by the ancient prophet Jeremiah as “deceitful above all things, and desperately wicked” (Jeremiah 17:9), cannot be trusted. The regenerate heart, on the other hand, can and should be trusted. In fact, by trusting it we are trusting the one who is dwelling and working within it (Ephesians 3:17, Philippians 2:12-13).

In order for the life-transforming truth of this volume to be understood, we must begin with the dispelling of a popular myth. What the Bible calls “the flesh” is almost universally interpreted to mean our old sinful or Adamic nature. Our sinful nature may best be defined as our natural inclination to sin. Given a choice between right and wrong the unregenerate man’s natural propensity is to do wrong. This inborn bent toward sin is widely believed to be retained by Christians after their conversion. Hence, we have the struggle of the Christian life. Our old nature—“the flesh”—pushes us to sin; our new nature—“the Spirit”—points us toward righteousness. We are tossed between the two as they pull us in opposite directions.

This erroneous belief is so commonly accepted that some modern translations of the Bible translate the Greek word for “flesh” as “sinful nature.” This attempt by modern translators to interpret Scripture rather than translate it is most unfortunate. It only serves to promote and perpetuate this false teaching of the Christian’s dual and dueling natures.

If what the Scripture calls “the flesh” is our old sinful nature, as the majority of Christians believe and most modern translations of the Bible assert, then Christ only makes a halfway difference in our lives. He does a halfway job. Although He gives us a new nature at conversion, He does nothing about our old one, leaving us as spiritual schizophrenics. This popular but foolish belief is refuted in 2 Corinthians 5:17 where the Apostle Paul teaches, “If any man be in Christ, he is a new creature, old things are passed away, behold, all things have become new.”

Our old nature or natural inclination to sin passes away when we come to Christ. It is replaced with a new nature, a divine one. According to the Apostle Peter, we become “partakers of the divine nature” in order to “escape the corruption that is in the world through lust” (2 Peter 1:4). In other words, partaking of the “divine nature” enables us to escape the world’s corrupt practices by rendering sin undesirable to us. Sin loses its luster and is no longer lusted after. Consequently, our natural propensity becomes the practice of righteousness. No longer are we prone to do what is wrong, but to do what is right and pleasing to God.

In Philippians 2:12-13, the Apostle Paul instructs us to “work out [our] own salvation with fear and trembling, for it is God that worketh in [us] both to will and to do of His good pleasure.” Notice, God is at work in us so that we will want to do, as well as end up doing, God’s “good pleasure” or what pleases Him. The Psalmist said the same thing in a different way when he wrote, “Delight thyself also in the Lord; and he shall give thee the desires of thine heart” (Psalm 37:4). Many have misinterpreted this verse to mean that God will give us whatever we desire. What this verse really teaches, however, is that God will give us “the desires” themselves. He will work in our hearts so that we will desire to do what pleases Him.

How do we “work out [our] own salvation with fear and trembling”? Obviously, we don’t work out our salvation by working for it. Christ has already done all the work that needs to be done for us to be saved. All that remains for us to do is accept by faith what Christ has done for us. When we do, we are saved by Christ’s work, not by any works of our own (Ephesians 2:8-9).

We cannot work for our salvation. Nevertheless, we are to work “out” our salvation. We work out our salvation by trusting God’s working within us and living out our daily lives according to the dictates of our hearts. By following our hearts we will be trusting God who is at work within them. This explains why the Apostle Paul says that our salvation must be worked out “with fear and trembling.” Working out in our lives the salvation that God is working in our hearts is tantamount to living our lives in a way that pleases God. It is not a matter of pleasing ourselves or pursuing our own fancies. It is a matter of us daily conforming externally to what God is performing in us internally.

In Colossians 2:6, the Apostle Paul teaches us that we are to live for Christ the same way we received Him. We received Christ by faith. We believed that His atoning work on the cross was enough to save us from our sins. We therefore trusted Christ to do for us what we could never do for ourselves. Now that we are saved from our sins, as a result of trusting in the sufficiency of Christ’s saving work on the cross, we must live our lives trusting in the sufficiency of Christ’s sanctifying work in our hearts. To put it more succinctly: We must stop trying to make our lives what they ought to be and start trusting Christ to do it for us.

When it comes to trusting Christ, we must not think of Him as being way up in Heaven. Thanks to the indwelling Holy Spirit, Christ is not only in Heaven, where He is seated at the right hand of the Father, but He is also in our hearts! This is why the Apostle Paul wrote, “But the righteousness which is of faith speaketh on this wise, Say not in thine heart, Who shall ascend into heaven? (that is to bring Christ down from above:) But what saith it? The word is nigh thee, even...in thy heart: that is, the word of faith, which we preach” (Romans 10:6, 8).

We don’t need to ascend into heaven to bring Christ down to help us. Christ is already with us. He is, as the Psalmist said, “A very present help in trouble” (Psalm 46:1). Christ is as near to us as our own hearts, since He lives within them in the person of the Holy Spirit. In light of this, all we need to do to live by faith in Christ is to live our lives following our hearts. Whenever we are following our hearts we are trusting in the sufficiency of Christ’s sanctifying work within us. On the other hand, whenever we are afraid to follow our hearts we are doubting the indwelling Christ.

In spite of this clear teaching from Scripture, we’re taught today that we must not follow our hearts, because our hearts cannot be trusted. After all, doesn’t Jeremiah 17:9 teach us that our heart is “deceitful above all things, and desperately wicked: who can know it”? Although Jeremiah accurately depicts in this verse the heart of a sinner, one who has not come to Christ, he is not describing the heart of a saint, one in whose heart Christ dwells (Ephesians 3:17). How could Christ possibly live in the deplorable living conditions described by Jeremiah in Jeremiah 17:9?

In Ezekiel 11:19-20 and 36:26-27, God talks about the New Covenant and promises to give us an “undividedheart,” as well as a “new spirit,” so that He can “cause” us to “walk” in His “statutes” and to “keep” His “ordinances” and “judgments.” He even promises to remove our “stony heart” and replace it with a “heart of flesh,” so that we will be His people and He will be our God. There you have it! The New Covenant does not promise us a heart torn between two natures, as is preached in today’s church, but a heart transplant, performed for us by the Great Physician.

Contrary to popular opinion, a Christian can follow his heart, since God has given him a new one at conversion. God gives the Christian a new heart so that Christ can take up residence within it. Christ cannot possibly move into our old sinful heart of stone. Therefore, God replaces it at conversion with a new heart so that Christ can have adequate living accommodations in our lives. Once Christ moves in, we can begin following our heart. When we do, we will be trusting Him who is living and working within it. By following our heart—living according to the dictates of the Spirit’s still, small voice within us—we will be living in the Spirit.