Hebrews 9:22 (ESV)
Without the shedding of blood, there is no forgiveness of sins.
To the unsaved, Christianity is a blood-and-gore religion. It is very violent, vulgar, and uncivilized. Its history is based on blood, death, and violence. Its founder (Jesus of Nazareth), leaders (Apostles), and many followers died bloody. Everything to do with Christianity is mired in blood where its founder demand that His followers drink His blood. To them, Christianity is too bloody to accept.
What such people fail to understand is blood is the essence of life. There can be no life without blood, and everything alive has blood flowing in it. Consequently, any supreme sacrifice, like the Lord who gave up His life for us, would require giving up the blood. Life can't be sacrificed if the blood is not spilled. The sacrifice for sins is death, which will not happen unless the blood is shed. The atoning sacrifice of the Lord Jesus, who symbolically died in our place, required giving up His life and blood. Without His blood, we'd have no part in Him.