Historically the Jewish people were required to sacrifice their best lamb in order to receive God's forgiveness. There were strict rules that had to be followed - day to day life rules AND sacrificial rules (the sacrifice had to be done in very specific ways). The crucifixion of Jesus wiped out all the sacrificial rules. Think back to when, even in more recent history, religious rules governed a society. Whether religious or not, the peoples of many countries have been forced to live under day-to-day life rules. It was burdensome (and impossible) to keep all the rules! Though Christians are required to follow some basic rules, the Bible tells us that His burden is light. Jesus brought us freedom. He's been called The Lamb of God.
Even though it seems archaic to us or even barbaric, all around the world sacrifices were standard. It was a system laid in place for centuries. A system for achieving God's forgiveness. So you see, by the time Jesus died there was already a working system. His death was just re-inventing the wheel - except for the fact that this spotless lamb didn't stay dead! And why does that matter? Before long, the world will not see me anymore, but you will see me. Because I live, you also will live. (John 14:19)
Jesus explained it to his closest friends:
If you're asking "how do I know the way?", read this.