13 For if the sprinkling of defiled persons with the blood of goats and bulls and with the ashes of a heifer sanctifies for the purification of the flesh, 14 how much more shall the blood of Christ, who through the eternal Spirit offered himself without blemish to God, purify your conscience from dead works to serve the living God. Heb. 9:13- 14
Messiah was offered through the eternal Spirit, the Greek word ainoios meaning eternal, unlimited duration of time.
And I will pray the Father, and he will give you another Counselor, to be with you for ever, John 14:16
The Greek word aion meaning forever, age, or universe and is where we get our eon. The word really has the idea of being beyond all creation, or greater than the transitory nature of the universe.