“And behold, the word of the LORD came to him: ‘This man shall not be your heir; your very own son shall be your heir.’
And he brought him outside and said, ‘Look toward heaven, and number the stars, if you are able to number them.’
Then he said to him, ‘So shall your offspring be.’
And he believed the Lord, and he counted it to him as righteousness.” —Genesis 15:4-6
When all you have is God’s covenant word, you already have all you need. Twice Yahweh comes to Abram repeating His covenant promises (15:1, 7). Twice Abram replies with a lament of faith mingled with doubt.
“O Lord GOD, what will you give me, for I continue childless, and the heir of my house is Eliezer of Damascus?…
O Lord GOD, how am I to know that I shall possess it?” (Genesis 15:2, 8; emphasis mine).
“What will you give?” While Yahweh does lead Abram to look at the stars, these simply serve as an illustration of the Word. When Abram doubts the Word, Yahweh gives him the Word. Abram has nothing more in his hand, but the Word is once again laid on his heart.
“How am I to know?” While Yahweh does formally establish a covenant with Abram at this juncture, nothing of the promise is realized. This covenant act is simply one reinforcing the covenant promises already made. God has spoken. Now He speaks louder as it were, still, this covenant act is essentially the promise spoken again. God had spoken. It will certainly be. He speaks again in this act to emphasize to Abram the certainty of His promise. When Abram doubts the Word, God still essentially gives him the Word.
All the days of our pilgrimage, the fullness of the promise will ultimately lie ahead of us. All the days of our pilgrimage, we will have nothing but the Word, sacraments, and our Lord’s covenant presence with us as His people. This is all we need. As we sojourn, as far as the promise of full and final deliverance from sin and of a land not marred by its curse, we have nothing but the Word. And in this, we have all that we need, for faith comes by hearing and hearing by the word of Christ. When you doubt the Word, cry out to your covenant Lord, that by His Spirit, He would minister the word of Christ to you afresh.
What has he given? He has given us Christ. He has given us His Word testifying of Christ.
How are we to know? He has given us Christ. He has given us His Word testifying of Christ.