1. The Covenants of Men
When an agreement was reached about wages of a penny a day, Matthew 20:13, the word used is συμθονεο, sumphoneo (sun, together, and phoneo to speak strongly). The same word is used when two agree together on earth about any matter, Matthew 18:19. Another, stronger word is used when the Jews agreed together, in council, to cast believers out of the synagogue, John 9:22, or to conspire against Paul and to murder him, Acts 23:20 - συντιτηεμι suntithemi (sun, together and tithemi, to lay down or establish). Yet another word is used when the Jews 'covenanted' with Judas for thirty pieces of silver to betray Jesus - 'ιστεμι, histemi (stand, set up, establish).
These are all agreements among men where parties negotiate and bargain and come to a conclusion.
None of these words are used, by the Holy Spirit's inspiration, in matters of the New Testament.
2. The New Testament
Instead, the word διαθεκε diatheke (dia through and theke, a secure containment) is used thirty three times in the Greek scriptures. Tyndale, in his 1534 New Testament, translated this word by 'testament' thirty one of those times. The KJV translators have chosen, unusually, not to conform to Tyndale on this particular matter and have only called it 'testament' twelve times.
The word διαθεκε diatheke is defined for us in Hebrews 9:16 and 9:17 where the writer says :
For where a testament is, there must also of necessity be the death of the testator.
For a testament is of force after men are dead: otherwise it is of no strength at all while the testator liveth.
The other types of agreement among men, above, are defined otherwise, as seen by the words used. But a διαθεκε diatheke, is defined for us in Hebrews 9:16 and 17.
The Testament which the Holy Spirit conveys through the writers of the Greek scriptures concerns a Testator and it only comes into force when the Testator dies. In fact, it is even stronger than that - it is prevented from coming into force until the Testator is deceased.
3. The Object of the New Testament
The objective was made clear six centuries before the birth of Jesus Christ in Bethlehem :
For this is the covenant that I will make with the house of Israel after those days, saith the Lord; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people: [Hebrews 8:10 and 10:16 KJV]
This prophecy, originally delivered through Jeremiah, 31:33, promises two things : an internal rule of the heart from God himself (and, therefore, it must be of Spirit) and a shared inheritance, that is to say an inherited relationship between Deity and corporate humanity.
Inherited, of course, after the death of Another.
It promises a better rule than that of the legal commandment. It promises a better human existence than one in Adam. It promises a better communal worship than that of external ritual and earthly government.
4. The Terms of the New Testament
The terms are not temporal, they do not relate to this present world. It is an 'everlasting covenant' Hebrews 13:20. The promises are not dependent on man's works or man's abilities. It is not a covenant with man, at all. It is promised; it is assured; it is everlasting.
And, more - Hebrews 9:15.
And for this cause he is the mediator of the new testament, that by means of death, for the redemption of the transgressions that were under the first testament, they which are called might receive the promise of eternal inheritance.
This testament is mediated. By the one mediator between Deity and humanity - Christ Jesus. There is no other name whereby men might be saved, than his name. He is the one who mediates it to every single needy soul who needs his mediation. And he does it personally - to each and every, single soul.
And by his mediation, the transgressions (which the first - 'old' - covenant could by no means remove) are thoroughly and utterly taken away by the shedding of his precious blood : Matthew 26:28 :
For this is my blood of the new testament, which is shed for many for the remission of sins.
5. The Beneficiaries of the New Testament
The 'many' referred to by Jesus, above, are clearly they whom Jesus also described as :
He that eateth my flesh, and drinketh my blood, dwelleth in me, and I in him.
. . . which is clearly not a matter of digestion, but of faith. And it is to 'he' - it is personal and individual, neither congregative nor corporate.
6. The Messenger of the New Testament
Mark makes it clear in the first verses of his gospel account that 'the beginning of the gospel' involves the ministry of John the Baptist (the baptism of repentance) and the coming of the one prophesied by Malachi - 3:1 -
... the Lord, whom ye seek, shall suddenly come to his temple, even the messenger of the covenant ...
Jesus Christ, the Lord, come in flesh, is the Messenger of the Covenant, he is the Testator of the New Testament, He is the Meidator of the New Testament and his is the blood of the Everlasting Testament.
7. The Inauguration of the New Testament
The rich man who wanted to pull down his barns and build bigger, Luke 12:18, used the word apotheke to describe a containment secure against animals foraging or thieves stealing his agricultural wealth. Apo is a matter of dimension - it's big.
Jesus uses the word theke when he tells Peter to put up his sword in its theke, John 18:11. More likely than a sheath, is a secure containment at home, bearing in mind what Jesus said about bearing a sword. Put it in its secure box at home : is what I understand to be his exhortation, but whatever - it is a secure containment.
As to the Testament - the diatheke - the 'through' theke - I suggest a coffin or a sepulchre is in view. A secure place to store a body until resurrection, is, I understand, to be the meaning.
The Testament comes into force through a securely contained body : in death.