Heb 9:15-17

Heb 9:15  And for this reason He is the Mediator of the new covenant [diatheke], by means of death, for the redemption of the transgressions under the first covenant [diatheke], that those who are called may receive the promise of the eternal inheritance.
Heb 9:16  For where there is a testament [diatheke], there must also of necessity be the death of the testator [diatithemai].
Heb 9:17  For a testament [diatheke] is in force after men are dead [epi nekros], since it has no power at all while the testator [diatithemai] lives.

The Greek word translated covenant is diatheke.  In the following two verses (16 and 17) it is translated testament.  The Greek word diatheke in verses 15 to 17 should be translated consistently as covenant.  A covenant is very different to a testament.  A covenant comes into force when the sacrifice sealing it dies.  A testament comes into force at the death of the testator.  A testament is a will.  Jesus Christ did not make a will describing the disposition of His possessions when He died.  Besides, if He did such a thing, would He then take back what He willed at His resurrection?  No, Jesus Christ made a covenant, an agreement that was sealed with His death.

Heb 9:15 – And for this reason He is the Mediator of the new covenant

The mediator was the person who witnessed the contract made between the two contracting parties, slew the sacrificial animal, and sprinkled each of the parties with the animal’s blood.  Jesus Christ is the Mediator of the new covenant, which is a covenant between God and all of humanity. 

Heb 9:15 – By means of death

It is by means of Jesus Christ’s death that we may receive the promise of the eternal inheritance.

Heb 9:15 – For the redemption of the transgressions under the first covenant

Jesus Christ’s death atoned for (or payed for) all the sins committed under the old covenant.  The blood of animals could not atone for the sins.

Heb 9:15 –That those who are called may receive the promise of the eternal inheritance

Those who are called are not just Israelites but also Gentiles.  The old covenant was between God and the nation Israel and promised physical blessings.  The new covenant is between God and all humanity which promises eternal life.

Heb 9:16 – For where there is a testament

The Greek word translated testament in this verse is the same word diatheke, that was translated covenant in the previous verse.  It should be translated consistently as covenant. 

Heb 9:16 –There must also of necessity be the death of the testator

The Greek word translated testator is diatithemai, (a verb), and it means to make a testament or covenant.  In light of how diatheke should be translated covenant, clearly diatithemai should be translated to make a covenant.  But with a covenant, it is not the covenantor (the person making the covenant) who needs to die, but the sacrifice.  This phrase is saying that there must be the death of that which makes or establishes (not performs) the covenant.  It is not saying that there must be the death of the covenantor (he who performs the covenant).  The confusion arises because Jesus Christ is both the covenantor and the sacrifice.

Heb 9:17 – For a testament is in force after men are dead

Again, the Greek word translated testament here is diatheke.  The phrase “after men are dead” is translated from the Greek epi nekros which literally means “over dead ones/things”.  The word “men” has been added by the translators.  This phrase is saying that the covenant comes into force after the sacrifice dies.

Heb 9:17 – Since it has no power at all while the testator lives

As in the previous verse, the Greek word translated testator is diatithemai, (a verb), and it means to make a testament or covenant.  In light of how diatheke should be translated covenant, clearly diatithemai should be translated to make a covenant.  This phrase is saying that the covenant has not power while the sacrifice lives.

Here are a couple of much better translations of verses 16-17.

Heb 9:16  For where a covenant is, the death of him having covenanted must be offered.
Heb 9:17  For a covenant is affirmed over those dead, since it never has force when he who has covenanted is living.
Literal Translation

Heb 9:16  For where a covenant is, there must be necessarily introduced the death of that which establisheth the covenant;
Heb 9:17  because a covenant is confirmed over dead things, and is of no force at all whilst that which establisheth the covenant is alive.
Wakefield

This is undoubtedly the meaning of this passage.  The translators should have translated diatheke consistently as covenant.