In Romans 3:21-26, Paul announces that law-logic can only announce the righteousness that God is and which therefore condemns us who have failed to conform to it. Then we arrive at chapter 4. The question that throws law and promise into a sharp contrast is this: How does one obtain the inheritance of the heavenly rest?  “But to him who does not work but believes on Him who justifies the ungodly, his faith is accounted for righteousness, just as David also describes the blessedness of the man to whom God imputes righteousness apart from works” (vv. 5-6).

What are you driven by? It was a Saturday and I flipped on the TV for an extraordinarily long time. The whole day was exercise equipment, how to become real-estate rich with no money down, and Suze Orman gave me her steps to financial security. As much as we all make sport of this sort of thing, it attracts us. That’s because we are “wired” for law: tell me what to do and I’ll get it done. That is not just the American spirit, but it is human nature. God’s law is inborn, in our conscience, part of our moral makeup.

The law can direct us, but it cannot drive us, except to either despair or self-righteousness. Christians are not purpose-driven but promise-driven. Purposes are all about law. The fact that purposes are about law does not make them wrong. We need purposes! All of this is fine as long as we realize that they are law, not gospel: commands and promises are both necessary, but they do different things. Church shouldn’t be a place where the old self is revived for another week, but where it is killed and buried and the new self is created in the likeness of Christ.

The church father Augustine defined sin as being “curved in” on ourselves. While imperatives (including purposes) tend by themselves to make us more “curved in” on ourselves (either self-confidence or self-despair), only God’s promise can drive us out of ourselves and our own programs for acceptance before ourselves, other people, and God. While the Christian life according to scripture is purpose-directed, it is promise-driven. Both of our passages-Genesis 15 and Romans 4-bring this point home powerfully.

Wrestling with the Promise (Genesis 15)

Even after his military victory and the remarkable event of being offered bread and wine with a blessing from Melchizedek, Abram’s greatest problem is that he has no heir, no one to carry on the calling that God has given him. His world, as he sees it anyway, is bleak. “After these things, the word of the Lord came to Abram in a vision, ‘Do not be afraid, Abram, I am your shield; your reward shall be very great’” (Gen. 15:1). Abram and Sarai had been called out of the barrenness of moon-worship in the city of Ur by God’s powerful Word, which created faith in the promise (12:1). Notice in this opening address, it is sheer promise. God simply declares, “I am your shield. Your reward shall be great.” 

Yet Abram wonders, “O Lord God, what will you give me, for I continue childless, and the heir of my house is Eliezar of Damascus? … You have given me no son, and so a slave born in my house is to be my heir” (vv. 2-3).

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