Question: : How are the Old Testament heroes in heaven? Who paid for King David’s sin and, if his sin was paid for somehow, can a good man in Africa who has never heard the Gospel also be in heaven?
Answer: Please read this article before this one. That will give you perspective on part of this question. For the rest, people mentioned in the Old Testament (heroes and non-heroes included) who believed the promise of God as it had been revealed to that point, were saved by the grace of God and their sins forgiven based on the anticipated atonement of Jesus Christ. Though they may have sacrificed an animal for their sin as God commanded, they were meant to realize that no animal can fairly be a substitute for my sin. Only I or another human being can die (or die in my place) for my sins (Hebrews 9:6-14).
Paul tells us in Romans 3:25-26 that God gave Jesus as an atoning sacrifice to demonstrate His justice in passing over sins committed previous to the coming of Christ. The forgiveness He was offering saints before the coming of Christ was based in the sacrifice Christ would make, so that God was just in forgiving sin before that. But each of those who were forgiven were believers. They were responding to the revelation God had given up to that point, whether the promise as it was stated in Genesis 3:15 or 12:1-3. The content of the promise was always being added to and expanded. But faith in that promise of God was always the means to receiving God’s salvation.
Today, the promise includes Jesus as the only mediator between God and man (1 Timothy 2:5-6). We must come through him now, must believe in him as God’s provision for forgiveness.