Sin is what you do when your heart is not satisfied with God. No one sins out of duty. We sin because it holds out some promise of happiness. That promise enslaves us until we believe that God is more to be desired than life itself (Psalm 63:3). Which means that the power of sin's promise is broken by the power of God's.
John PiperThe engagement of the heart in worship is the coming alive of the feelings and emotions and affections of the heart. Where feelings for God are dead, worship is dead.
John PiperIf God were not just, there would be no demand for his Son to suffer and die. And if God were not loving, there would be no willingness for his Son to suffer and die. But God is both just and loving. Therefore his love is willing to meet the demands of his justice.
John PiperLove is the overflow of joy in God! It is not duty for duty's sake, or right for right's sake. It is not a resolute abandoning of one's own good with a view solely to the good of the other person. It is first a deeply satisfying experience of the fullness of God's grace, and then a doubly satisfying experience of sharing that grace with another person.
John Piper