The Blood of Christ refers to the spiritual death of Christ on the Cross.
The blood of Christ is figurative of his spiritual death — His sacrifice for sin. Our Lord did not bleed to death, nor did man “kill God.” His “blood” refers to His “Spiritual death-payment.”
When the penalty of sin was completely paid, Christ said, “It is finished.” (Please notice: He was alive when He said this.) And when He said, “It is finished,” He was referring to our salvation.
So, physical blood and death was not the payment for sin. He died spiritually, immediately, when all sin was poured out on Him on the cross during the three hours of total mid-day darkness. He died physically when He dismissed His spirit, (not by bleeding to death), after salvation was finished. Then, because salvation was paid, there was no reason left for Him to remain on the cross in suffering and shame, so He dismissed His spirit (John 19: 28&30).