Abraham believed God, and it was counted to him as righteousness. ( Romans 4:3 3 For what saith the scripture? And Abraham believed God, and it was reckoned unto him for righteousness. )

Paul makes it plain that already in the Old Testament, those who were truly God’s children were justified in advance by the work of Christ. That is the point of Romans 3:21 21 But now apart from the law a righteousness of God hath been manifested, being witnessed by the law and the prophets; –26. He gives Abraham and David as examples. “Abraham believed God, and it was counted to him as righteousness” ( Romans 4:3 3 For what saith the scripture? And Abraham believed God, and it was reckoned unto him for righteousness. ). “David also speaks of the blessing of the one to whom God counts righteousness apart from works” ( Romans 4:6 6 Even as David also pronounceth blessing upon the man, unto whom God reckoneth righteousness apart from works, ).

Therefore, the true Old Testament saints (who were all justified sinners) were granted to see that law-keeping was not the basis of their right-standing with God. Instead, they could look upon the commandments of God as a gift of God’s guidance for their good ( Deuteronomy 10:13 13 to keep the commandments of Jehovah, and his statutes, which I command thee this day for thy good? ), and they could pursue obedience by faith — a faith that alone was their link to the justifying, covenant love of God.

They could see, woven through the law of commandments, the provisions of forgiving and justifying grace. And they knew that they needed this grace because of their sins.

But they could also see that the law’s provision of sacrifices was not the final answer to their need. “In these sacrifices there is a reminder of sins every year. For it is impossible for the blood of bulls and goats to take away sins” ( Hebrews 10:3 3 But in those `sacrifices' there is a remembrance made of sins year by year. –4). “You will not delight in sacrifice, or I would give it; you will not be pleased with a burnt offering” ( Psalms 51:16 16 For thou delightest not in sacrifice; else would I give it: Thou hast no pleasure in burnt-offering. ; see also 40:6).

They knew that “no man can ransom another, or give to God the price of his life [how much less an animal!], for the ransom of their life is costly and can never suffice” ( Psalms 49:7 7 None `of them' can by any means redeem his brother, Nor give to God a ransom for him; –8). They glimpsed afar off that God would one day provide a Redeemer, who would be “pierced for our transgressions . . . crushed for our iniquities.”

In that day they would say, “The Lord has laid on him the iniquity of us all” ( Isaiah 53:5 5 But he was wounded for our transgressions, he was bruised for our iniquities; the chastisement of our peace was upon him; and with his stripes we are healed. –6).