“Behold, I am coming quickly, and My reward is with Me, to render to every man according to what he has done. I am the Alpha and the Omega, the first and the last, the beginning and the end.The Spirit and the bride say, ‘Come.’ And let the one who hears say, ‘Come.’ And let the one who is thirsty come; let the one who wishes take the water of life without cost.”

Kainos Diatheke, Renewed Covenant

For this is My blood of the covenant, which is shed for many for the remission of sins.

Matthew 26:28 NKJV

And He said to them, This is My blood of the new covenant, which is shed for many. 

Mark 14:24 NKJV

Likewise He also took the cup after supper, saying, This cup is the new covenant in My blood, which is shed for you.

Luke 22:20 NKJV

As you can see, in the gospels of Luke and Mark, there is a cup of the new covenant given in His (Yeshua’s) blood. There are two Greek words for new. One is neo(s) and the other is kainos.

Neo(s) is defined as brand new, fresh, or young, as in young persons; it can mean recent. 

Kainos is described as refreshed, renewed, repaired, or qualitatively new.

Equivalent to kainos is the Hebrew word chadash, meaning to renew, repair, rebuild. The Aramaic word would be khawdata.

Diatheke is the Greek word for covenant, and the Hebrew term for it is b’rit. 

Some of our translations, like the King James Version, add new in two of the three gospels to covenant. However, in the Greek manuscripts new/kainos is omitted from the original texts of both Matthew and Mark

Here is what the Nestle-Aland has for Matthew 26:28 in Greek from the English-Greek Reverse Interlinear New Testament, ESV 

28. gar touto estin mou To haima tes diathekes To ekchynnomenon peri pollon eis aphesin hamartion

Translated it says: gar (for) touto (this) estin (is) mou (my) To haima (blood) tes (of the) diathekes (covenant) To ekchynnomenon (which is poured) peri (out for) pollon (many) eis (for) aphesin (the forgiveness) hamartion (of sins). 

. . .for this is my blood of the covenant which is poured out for many for the forgiveness of sins. 

Mark 14:24

Kai (and he) eipen (said) autois (them) touto (this) estin (is) mou (my) to haima (blood) tes diathekes (covenant) to ekchynnomenon (poured out) hyper (for) pollon (many).

Luke 22:20

Touto (this) to plterion (cup) to ekchynnomenon (poured out) hyper (for) hymon (you) he (the) kaine (new) diatheke (covenant) en (in) mou (my) to haimati (blood).

Some manuscripts insert kaine, new. Footnote from the Nestle-Aland.

Matthew, according to the Nestle-Aland Novum New Testament, did not include the Greek word kaine. The Gospel of Matthew is the first to have been written on the account of Yeshua’s life and ministry. Mark was written later at the request of Peter. 

The church historian Eusebius relied on an earlier writer named Papias, bishop of Hierapolis (c. 60-130) who wrote about this around the year 120:

“Mark, having become Peter’s interpreter, wrote down accurately whatever he remembered of what was said or done by the Lord, however not in order.”

He declared that “Matthew had begun by preaching to the Hebrews, and when he made up his mind to go to others too, he committed his own Gospel to writing in his native tongue [Aramaic], so that for those with whom he was no longer present the gap left by his departure was filled by what he wrote” (History of the Church 3:24 [inter 300-325]). 

Some say Matthew was copied from Mark, and that Matthew filled in with some extra details. However, their views differ on their presentation of the Messiah. Matthew’s gospel was an eye-witness account, and Mark wrote his account from Peter. Matthew has more Old Testament quotes than Mark. So, differences and similarities can be made in both accounts. 

Whatever debate between scholars might exist on which was produced first, the Greek manuscripts of Matthew and Mark agree that Yeshua’s blood was of the covenant, not a new covenant. The writer (manuscript) of Luke understood the Covenant was being kaine, renewed. Translators do not appear to capture this nuance for the readers of the Bible, and they (readers) make incorrect assumptions from this which gives way to teaching error. By this I mean, some would think Yeshua made a brand-new covenant or brand-new religion, which He did not do.  

So, from the manuscripts we can see there was no new covenant, and Luke lends to us a refreshed or renewed covenant. 

Since there is no new covenant, which covenant is Yeshua referencing in Matthew 26:28?

His disciples would have understood it was the Mosaic Covenant given at Mt. Sinai in Exodus. 

Exodus 24

So Moses came and told the people all the words of the Lord and all the judgments. And all the people answered with one voice and said, “All the words which the Lord has said we will do.” And Moses wrote all the words of the Lord. And he rose early in the morning, and built an altar at the foot of the mountain, and twelve pillars according to the twelve tribes of Israel. Then he sent young men of the children of Israel, who offered burnt offerings and sacrificed peace offerings of oxen to the LordAnd Moses took half the blood and put it in basins, and half the blood he sprinkled on the altar. Then he took the Book of the Covenant and read in the hearing of the people. And they said, “All that the Lord has said we will do, and be obedient.” And Moses TOOK THE BLOOD, SPRINKLED IT ON THE PEOPLE, AND SAID, “THIS IS THE BLOOD OF THE COVENANT WHICH THE LORD HAS MADE WITH YOU ACCORDING TO ALL THESE WORDS.”

There are about twenty-two covenants in the Bible. The covenant cut at Mt. Sinai was, I think, the fifth covenant and established the religion of Israel. God’s Torah, the Ten Teachings (Commandments), would be the law of the land, or the nation. God required obedience in order for a relationship to exist between Him (who delivered them from Egypt) and the nation of Israel.

Exodus Chapter 24: Seven Elements to a Covenant Relationship with God (inspiredscripture.com)

The author of Hebrews expands on the account given in Exodus 24.

Hebrews 9:15-20

15. For this reason, He is the intermediary of a renewed (kaines) covenant relationship, in order that those who have been called may obtain the promise of the eternal inheritance. All of this happened because a death has taken place securing an atoning redemption for the transgressions which were done under the earlier covenant relationship. 

16. In the case where a last will and testament is involved, the death of the one who made the will must be validated. 

17. So then, a will as a covenant agreement takes effect only at death because it is never in force while the one who made it lives.

18. Even the earlier covenant relationship was not regularly renewed without blood.

19. When every commandment had been spoken by Moshe (Moses) to all the people, in accordance with Torah, he took the blood of the calves and the goats, together with water, scarlet wool, and hyssop. He sprinkled both the scroll itself and all the people as well,

20. declaring, “This is the blood of the covenant relationship which God commanded you”. Moreover, in the same way, he sprinkled blood over the Tent of Meeting and all the vessels used in the worship service. The Newer Testament, Dr. Brad Young

The Nestle-Aland text has for Hebrews 9:15

Kai dia touto (Therefore he) estin (is) mesites (mediator) kaines (renewed) diathekes (covenant), hopos (so that) hoi (those) keklemenoi (called may) labosin (receive) ten (the) epangelian (promised) aioniou (eternal) tes kleronomias (inheritance).

Hebrews 9:20

Legon (saying), touto (This is) to (the) haima (blood of) tes (the) diathekes (covenant) hes (that) ho theos (God) eneteilato (commanded) pros (for) hymas (you).

Verse 15 has kianos which is renewed. These verses only speak of the covenant, and the author of Hebrews understands that Yeshua’s blood is renewing the former covenant. Only His blood has the capacity to seal it permanently, whereas the blood of calves, goats, hyssop, water and scarlet wool renewed it every year. His blood alone gives eternal life. Our responsibility, like Israel, is to be obedient to His Teachings, all the ethical and moral standards set forth in the Torah. Israel entered the Covenant with the LORD by saying: All that the Lord has said we will do, and be obedient.” 

Behm contrasts neos and kainos: “Meaning ‘belonging to the present,’ néos has the nuances of ‘fresh’ and ‘young.’ . . . The reference is to a new age, whereas kainós would suggest a new nature . . . “ (“Néos” 628). He goes to observe that “[u]nlike kainósnéos does not have an eschatological content in the NT. It refers to the new reality of present salvation” (628).

Terms for Newness – Word-Smith.info

The letter of Hebrews lays the foundation for the priesthood becoming obsolete, making way for the eternal ministry of Yeshua. There was no fault in the Older Covenant, just the priesthood. 

Some would perhaps surmise that Yeshua made a brand-new religion, when instead, He strengthened the former covenant. The older sacrificial system could not cover intentional sins. Yeshua’s blood is able to cleanse one of all sins having been committed, whether unintentional or intentional. Intentional sins were adultery, fornication, sacrificing children, homosexuality, idolatry, zoophilia, satanism, witchcraft, necromancy, sex with parents, other family members, etc. The first covenant sacrifices (Mt. Sinai) were established for unintentional sins. Yeshua’s atoning blood made a way of entrance into the kingdom of His Father for all who would want to repent among the nations, those who would be sick of their sins and receive Him, those who desire eternal life.

Summary

Yeshua’s sacrificial blood renewed the Sinai Covenant in Exodus 24. That Covenant (B’rit, means to cut) was sealed by the blood of animal sacrifices, and was a temporary solution for the remission of sins; that is, unintentional sins. 

Yeshua’s blood is able to cleanse a sinner from all unrighteousness, unintentional and intentional sins. He forged a path for one who walked alien to the laws of righteousness to come into a Covenant with Him. That agreement though, like Israel, had to be based on obedience. They could not be hearers only, but doers (practice) of the Word, or Law. James 1:22

They said: All that the Lord has said we will do, and be obedient.”  Exodus 24:7

The LORD had given the Mosaic Covenant which consisted of words. Words in Hebrew is devarim, and the devarim given in Exodus 24 were His commandments. Christians understand it to be the Decalogue or Ten Commandments. The LORD then gave an expanded, more precise, understanding of these devarim throughout Torah. 

The Covenant at Mt. Sinai speaks of deliverance. Israel was delivered from the dead works of Egypt, and idolatry. Israel was then to walk in obedience before their God (I AM, Ehyeh Asher Ehyeh). To walk in obedience means to practice righteousness before God who sees all that we do.

Yeshua’s blood speaks of deliverance from the system of dead works and idolatry. He became a mediator of the Renewed Covenant, so that by His death He would become the deliverance for those who have transgressed against the first covenant, that those who were called to have the eternal inheritance should receive that promise. 

In Hebrew the Christian New Testament would be the B’rit Chadasha. In Greek it would be Kainos Diatheke. In English it would be Renewed Covenant. 

We are living the Renewed (Kainos) Covenant (Diatheke) where we can receive eternal life through His sacrifice, His blood, and free to practice obedience to His Teachings. 

It is evident from the word that we must be doers of the Word (devarim) and not hearers only. Once we decide to be in Covenant with God, we also take the responsibility to practice His Word. James 1:22

The Authorship of Mark’s Gospel: Who Was Mark? (learnreligions.com)

Nestle Aland | Theopedia

The Gospel of Matthew vs. the Gospel of Mark | Free Essay Example (studycorgi.com)

Summary of the Gospel of Mark – Bible Survey | GotQuestions.org