the blood

RC Sproul writes the following in Now, That's a Good Question!

The idea that there's some intrinsic or inherent power in the blood of Jesus is a popular concept in the Christian world. It even crops up from time to time in various hymns and praise songs. This idea reflects a fundamental misunderstanding of the concept of the blood as it relates to atonement from a biblical perspective.

I once heard my dear friend John Guest, who is an Anglican evangelist, preach on the cross of Christ and on the blood of Christ. He asked this question: "Had Jesus come to this earth and scratched His finger on a nail so that a drop or two of blood was spilled, would that have been sufficient to redeem us? That would have constituted the shedding of blood. If we're saved by the blood of Christ, wouldn't that have been enough?" Obviously the point John was trying to make is that it's not the blood of Christ as such that saves us.

The significance of blood in the sacrificial system is that it represents life. The Old Testament repeatedly makes the point that "the life of the flesh is in the blood" (Lev. 17:11). Therefore, when the blood is poured out, the life is poured out. That's significant, because under the covenant of works in the garden, the penalty that was laid down for disobedience was death. God required that penalty for sin. That is why Jesus had to die to accomplish the atonement. When the blood is shed and the life is poured out, the penalty is paid. Nothing short of that penalty will do.