Scripture says that everywhere God has made his existence known to all men. All men, everywhere, and in all times, all Dispensations, know/have known His basic rules for behavior — those things described in the Ten Commandments. Yet, during the entire history of Man, he has been a sinner; he has violated God’s commandments. “There is none good…” No person bearing the taint of unforgiven sin can be admitted to the Presence of God. So prior to the Cross, by what means was sin forgiven? God tells us that it is not by the blood of animals but, nevertheless, sin is not forgiven without the shedding of blood. Exactly what was the purpose, the function, of animal sacrifices in antiquity and, later, in the Temple? How was a man made pure and able to be admitted to the Presence after death?
Before the cross people were saved by the blood of Jesus just like we are. They didn’t know His name and He hadn’t died yet but they believed from their Scriptures that He would, just like we believe from our Scriptures that he did. The sacrifices they were required to offer served as evidence of their faith. In fact, if the sacrifices were not offered in faith, it did them no good to offer them. But even then, their sins weren’t totally forgiven, they were just set aside until the Lord actually died for them. At that point His blood was applied and they were clean. That’s why believers who died before the cross went to Sheol instead of Heaven. The first time those believers were in the Presence of God was the afternoon of the Lord’s death when He showed up among them.