By sipping tea every afternoon, changing my accent, and learning the words to the British national anthem, I can resemble a British citizen without every becoming one. Becoming a British citizen and living as a British citizen, and living under the Queen’s rule involves more than simply resembling a British citizen.

Similarly, focusing on changing our external behavior to resemble a citizen of God's kingdom is not enough. Telling people to be content with their financial situation, forgive others, stop worrying, and start trusting God are all good things to do. But they are impossible things to do without experiencing an inward transformation that makes those behaviors both desirable and habitual. Until we realize that, we will sentence ourselves to a lifetime of mopping up the messes that emanate from a heart that has not been transformed.

The essence of discipleship is a changed life that comes from a transformed heart. But before we can have a transformed heart, we need to have a biblical understanding of our hearts.

1. Our hearts determine our behavior 

First, our heart (thoughts, feelings, will) determines our behavior. Acts of sexual immorality, financial dishonesty, violence, or deception are not involuntary responses. Instead, they are the natural byproduct or "fruit" of the kind of heart we have. As Jesus said in Matthew 12:35: “The good man out of his good treasure brings forth what is good; and the evil man out of his evil treasure brings forth what is evil.”

To attempt to change a person's behavior without changing the condition of his or her heart is an exercise in futility. For example, how many diets have you started . . . and quit through the years? How many New Year's resolutions have you kept past January? Any attempt to instigate, eliminate, or modify behavior that does not deal with a transformation of our heart – our thoughts, affections, as well as our will, WILL fail.

2. Our hearts have been polluted

Second, our hearts have been polluted. In Genesis 6:5, God offers this analysis for the condition of man's heart: “Then the LORD saw that the wickedness of man was great on the earth, and that every intent of the thoughts of his heart was only evil continually.”

You and I have inherited diseased, defective hearts. Probably the best term to describe the condition of our heart – and therefore the condition of us – is "ungodly." The term "ungodly" is used as a designation not just for the dregs of humanity such as child abusers, murderers, and drug addicts. Instead, the term is a general classification of the entire human race.

Jesus did not die just for the worst of humanity, but for all of humanity, including each of us. To be ungodly means to be against God in our thoughts, our will, and our emotions. That is the natural condition of our heart. We are predisposed to oppose God. Admittedly, that is an uncommon and unpopular diagnosis. Yet, all you have to do is look around you and within you to realize it is an accurate diagnosis. 

3. Our hearts can be transformed 

The Old Testament anticipated the time when God would perform a heart transplant for His followers: “And I shall give them one heart, and shall put a new spirit within them. And I shall take the heart of stone out of their flesh and give them a heart of flesh, that they may walk in My statutes and keep My ordinances and do them. Then they will be My people, and I shall be their God (Ezekiel 11:19-20).”

Notice the sequence here. Above all things, God desires our obedience – walking in His statutes and keeping His ordinances. But that radical change in our behavior will never occur without a new heart. 

God has already given you everything you need to live the kind of supernatural life that Jesus Christ lived. But possessing those spiritual resources does not automatically ensure spiritual transformation. God supplies the power, but you must supply the effort. Without God's power, we cannot become like Christ. Without our effort, we will not become like Christ.