See Luke 22:20; 1 Cor. 11:25; 2 Cor. 3:6, 14; Heb. 9:15; 12:24.
The word _Testament_ means _Covenant,_ and is the term
by which God was pleased to designate the relation that existed
between Himself and His people. The term _Covenant_ was first
of all applied to the relation itself, and afterward to the books
which contained the record of that relation.
By the end of the second century we find the "Old Covenant" and the
"New Covenant" as the established names of the Jewish and Christian
Scriptures; and Origen, in the beginning of the third century, mentioned
"the divine Scriptures, the so-called Old and New Covenants."
The Old Testament deals with the record of the calling and history
of the Jewish nation, and as such it is the Old Covenant. The New
Testament deals with the history and application of the redemption
wrought by the Lord Jesus Christ, and as such it is the New Covenant.