How were people saved who lived under the Law?
The writer of Hebrews (presumably Paul) contrasts the Law, which Moses presented to God’s people, with the New Covenant, which came into effect after the death of Christ. Under the Law, the people were commanded to offer certain sacrifices for their sins. These sacrifices atoned for their sins, and God granted the people forgiveness.(1) These sacrifices, however, could not permanently take away their sins.(2) Once a year, every year, the high priest was required to enter the Most Holy Place in the Tabernacle and make a special atonement for all the sins of the Israelites.(3)
To better understand how the atonement process worked, you can think of the sacrifices made under the Law as being similar to the payments made on an interest-only loan. When you take out an interest-only loan, your payments are only for the interest due during that time period. All of the principal on your debt remains outstanding. Usually, the interest-only period lasts for only a few years before you’re required to start paying on the principal or refinance. Theoretically, you could pay on such a loan forever and never repay any of your debt, provided you could find a lender willing to hold such a loan. The interest payments made during the interest-only period simply keep you in good standing and prevent foreclosure on your loan.
That’s how it was for God’s people who lived under the Law. The debt that sin incurred was too great for any of them to ever repay. Their sacrifices only covered the interest due at the time but could never eliminate their debt. God was willing to grant them such a loan because He already had a plan in place. He knew that one day Someone would be willing and able to repay their debt in full for them—His Son, Jesus Christ. When Jesus died on the cross, His sacrifice covered not only the sins of all who would believe on His name in the future living under the New Covenant but also the sins of the faithful who had died under the Law.(4)
Footnotes:
(1) Leviticus 4 describes sin offerings. When God’s directives were followed, the offerings the priests made on behalf of others provided atonement for their sins, and they were forgiven. (See verses 19–20, 26, 31 and 35.) Leviticus 5 describes other circumstances which required offerings, and again, atonement would be made and forgiveness granted. (See verses 10, 13, 16, 18.)
(2) See Hebrews 10:1–4 (NIV): “The law is only a shadow of the good things that are coming—not the realities themselves. For this reason it can never, by the same sacrifices repeated endlessly year after year, make perfect those who draw near to worship. Otherwise, would they not have stopped being offered? For the worshipers would have been cleansed once for all, and would no longer have felt guilty for their sins. But those sacrifices are an annual reminder of sins. It is impossible for the blood of bulls and goats to take away sins.”
(3) The yearly Day of Atonement is described in Leviticus 16. In verse 34 (NKJV), God commanded that it was to be done year after year: “This shall be an everlasting statute for you, to make atonement for the children of Israel, for all their sins, once a year.”
(4) See Hebrews 9:15 (ESV): “Therefore he is the mediator of a new covenant, so that those who are called may receive the promised eternal inheritance since a death has occurred that redeems them from the transgressions committed under the first covenant.”