We often make a distinction between the law (or the Old Testament) and Gospel (or the New Testament), which is simply unfounded. We make much of the Old Testament’s requirements for obedience to the law of Moses and little of Israel’s call to faith. It is only in the New Testament, we reason, that faith is clearly the basis by which we are justified before God.
However, both testaments speak of God’s grace and requirement of faith. The problem is that we simply read the New Testament too much and miss the clarion call for faith in God as the means of justification in the Old Testament.
In fact, much of Old Testament concerns faith (or belief) and trust in God, while living under the law. Five key events really bring faith and trust in God into the foreground in the Pentateuch (i.e. Genesis–Deuteronomy).
First, Abram believed God and it was credited to him as righteousness (Gen 15:6). His belief was a simple trust that God would do what he said (Gen 15:5). After Abram believed, God gave him the sign of the covenant (15:7–19). God always is a rewards those who believe in him (Cf. Heb 11:6).
Second, Israel’s Exodus was about faith. When God called Moses to free his people, Moses worried that the people would not “believe” God’s message through him (cf. Ex 4:1, 5). Thus, God provides a sign to confirm God’s promises (cf. Ex 4:8 [2x], 9). The Exodus event begins by belief in God’s promise of Deliverance. If Israel believed, they would be delivered from captivity.
Third, the covenant at Sinai concerns faith. It is not a random occurrences that immediately after God tells Israel to be a kingdom of priests and before the giving of the Decalogue, that the theme of faith pops up again. When God comes he will speak through Moses so that the people will “believe” him forever (Ex 19:9). The sign to confirm God’s promise is a dark gloomy could over the Mount (Ex 19:9).
Fourth, Israel’s wilderness rebellion is akin to unbelief in God. For this reason, God has said, “How long will this people despise me? And how long will they not believe in me, in spite of all the signs that I have done among them? (Num 14:11)” Again, the issue is belief or faith in God. On top of this, God has provided ample signs so that the people should trust in his power by now.
Fifth, the reason Moses and Aaron did not enter into the land was because of unbelief. “And the LORD said to Moses and Aaron, “Because you did not believe in me, to uphold me as holy in the eyes of the people of Israel, therefore you shall not bring this assembly into the land that I have given them.” (Num 20:12). Again, the issue is unbelief. Of course, the sign of flowing water should have been an ample sign for Moses to believe (Num 20:10–11); yet, it was not.
These select examples demonstrate the Old Testament focuses on Israel’s call to faith. If we read the context of these passages, we will soon realize that these are key narratives throughout Pentateuch (Exodus, Sinai covenant, entering the land, etc.). Moses placed these calls to faith and trust in God in key places to show the necessity of faith in the Pentateuch.
Don’t shortchange the Old Testament by making it about works-salvation, while the New Testament is about faith. Both Testaments testify that God seeks those who exercise faith and trust him.