The word testament means covenant. Thus, the Old Testament means the old covenant.
Jesus explained the new covenant during the last supper, in Matthew 26:27-28, after he broke the bread:
“Then he took a cup, and when he had given thanks, he gave it to them, saying, ‘Drink from it, all of you. This is my blood of the covenant, which is poured out for many for the forgiveness of sins.’”
While instructing the Corinthians about the Lord’s Supper, Paul repeats Jesus’s words. 1 Corinthians 11:25 says:
“In the same way, after supper he took the cup, saying, ‘This cup is the new covenant in my blood; do this, whenever you drink it, in remembrance of me.’”
In Hebrew 8, where the author writes extensively about the old and new covenants, he states in verses 6 and 7:
“But in fact, the ministry Jesus has received is as superior to theirs as the covenant of which he is mediator is superior to the old one, since the new covenant is established on better promises. For if there had been nothing wrong with that first covenant, no place would have been sought for another.”
The new covenant is what the New Testament is all about.
