Some non-Christians, mainly Muslims, ask why Jesus had to die on the cross in order for us to be saved. "Why does God need a blood sacrifice?" They'll ask, "Why can't He simply just forgive us?"
This objection was recently posed to me in the comment section in another article in this sight. This fellow said "God is the one who set up this system of sacrificial atonement. This is where I began to have serious doubts about the authenticity of the Bible as the Word of God. I can see a primitive sect of people setting up a system this way since they were familiar with various tribes that thought sacrificing a baby or a virgin would appease the gods. But it is hard for me to accept that the real God of the universe who has all knowledge and power would ever resort to such a bloody, painful and grotesque practice. It makes no sense that he would require the death of someone to atone for the sins of the world. He could have set this system up anyway he wanted to. He could just forgive us like we forgive others. When someone wrongs me, I do not require a blood sacrifice. Generally a simple 'I'm sorry, please forgive me' will do. But that is not good enough for God. He requires death."
How should we answer this?
I think this makes more sense if you think of God's ridding our sins as a discharging of debt. Imagine you have violated the law and face a $50,000 fine. You tell the judge that you are truly sorry for your crime, but the judge responds "I certainly hope so. You've violated the law. Now, pay this fine." You respond "No, I cannot. This debt is too much for me to bare. I promise I won't do it again. Just please forgive me." and the judge says "I can't do that. The law requires that you pay this fine or face prison. I would be a corrupt judge if I just let you off Scott free. Someone has got to pay the penalty." You begin to despair because you know the judge cannot just simply forgive you, but neither can you save yourself from this massive debt. Suddenly, something takes you by surprise. The judge steps down from his bench and walks over to you. Then he reaches into his pocket and takes out his wallet, handing you $50,000 in cash saying that he will pay the fine for you (should you accept his offer).
This is analogous to our sin situation. We have all strayed from God’s laws (Romans 3:23), and are therefore guilty before Him, deserving death (Romans 6:23a). God has to punish evil because He is just (Psalm 9:7-8, Psalm 9:16, Psalm 11:16). If He did not punish us, He wouldn’t be a just judge, just as the judge in the illustration above wouldn’t be just if he had let the fine go unpaid. So God must punish us. However, God is also loving (1 John 4:8, 1 John 4:16) and therefore desires not to punish us for our crimes. Just like the judge in the above illustration, God stepped down from His throne, taking on human flesh (John 1:14, Philippians 2:5-8), and was punished in our place. He accrued the penalty to Himself by being crucified.
However, Jesus’ death is a necessary condition, but not a sufficient condition for salvation. Repentance is required for Christ’s death to be efficacious (Isaiah 55:7, Acts 3:19). If we reject Him, God’s wrath will remain on us (John 3:18, John 3:36). Just as if you were to reject the judge’s offer to pay your fine for you, if one rejects Christ, our sin-debt will remain unpaid.
Regarding animal sacrifices prior to Jesus' death, I think these are analogous to credit cards. Credit cards don't actually pay for anything, but they allow you to walk out of the store with your desired object until you have the money to pay for it. Likewise, animal sacrifices never discharged our sin-debt before God (Hebrews 10:4), but they were a sign to God that you were repentant and trusted in Him for salvation. God retroactively applied Jesus' sacrifice to these Old Testament individuals.