And so, Jesus came to His own, the people of Israel, prepared to pay that high price. He came with the New Covenant, to sign it with His blood. The expression, "signed in blood", is thoroughly biblical. When God made covenants in the past with Abraham, Moses and so forth, He had animals sacrificed and the blood sprinkled to ratify the covenant. Jeremiah had only prophesied the advent of the New Covenant; Christ came to sign it and present it.
We see Him drinking the cup with His Bride in Matthew 26:27. It was the Passover table that the Lord did this so appropriately. He was to die that day (the next morning actually, but the Jewish day begins at sundown). He took this last opportunity to drink the cup with His Bride and seal the New Covenant:
And He took the cup, and gave thanks, and gave it to them, saying, Drink ye all of it; For this is my blood of the New Testament, which is shed for many for the remission of sins (Matt. 26: 27-28)
Looking at verse 27, we might ask, "What did the Lord say when He gave thanks?" Any Jew can tell you - there is just one Jewish blessing over the wine and it has been said for all time.
Blessed art Thou, O Lord our God, King of the universe, Creator of the fruit of the vine.
The fruit of the vine, ultimately, is the Church. Jesus said that He was the true vine, and the disciples were the branches. Finally, we become the fruit in this figure, and this brings out the toast aspect of this cup. Jesus praised the Creator for bringing forth this Bride and He toasted the Bride for becoming the true fruit. Then He told all the believers to drink this cup so that they would answer His proposal affirmatively and become His promised Bride.
In verse 28, He announced that the cup was His blood of the New Covenant ("testament" and "covenant" are the same word), and that it is shed for the remission of sins. Obviously, this fulfilled Jeremiah's announcement of the New Covenant - the covenant which would forgive sins. It's interesting to consider that the New Testament itself is our copy of the contract. Should anyone accuse you of sin, you need only show him your copy of the contract to prove that your sins are forgiven. Should the devil himself accuse you, and Satan is the "accuser of the saints", quoting the terms of the New Testament will settle the matter. You are "bought with a price". Your next responsibility after receiving the Bridegroom is to go about, in proper modesty with your veil, honoring the covenant you have made, in the manner of a virgin bride awaiting her promised bridegroom. You are not to make further sacrifices to impress God. Jesus made it very clear that this one sacrifice - this one cup - would be sufficient to forgive everyone's sins, all the way up to the Kingdom of God:
But I say unto you, I will not drink henceforth of this fruit of the vine, until that day when I drink it new with you in my Father's Kingdom (v.29)
We are responsible to God for good works. We are more than a bride; we are also workers in a field. But insofar as our salvation goes, it has been bought and paid for and we cannot lose it or enhance it in any way according to this contract.
For by grace are ye saved through faith; and that not of yourselves; it is the gift of God: Not of works, lest any man should boast (Eph. 2:8-9).