For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God. – 2 Corinthians 5:21
God is holy. Because of his holiness, he can not stand sin. Man is sinful. Because of his sinfulness, he can not stand in God’s presence. Somehow we needed to be made right with God.
The penalty of sin is death. Romans 6:23
Someone had to pay the price for sin. The Bible says that Jesus, who knew no sin, became our substitution. Much like how someone might pick up the tab for us at a restaurant. Jesus, paid our sin price and he paid that price with his blood. When we accept Jesus as our savior we are symbolically covered by his blood. When God looks at us, instead of seeing our sin, he sees the righteousness of Christ. Because of this we can now stand in God’s eternal presence.