Eternal Spirit
Hebrews 9:14 KJV – How much more shall the blood of Christ, who through the eternal Spirit offered himself without spot to God, purge your conscience from dead works to serve the living God?
The eternal Godhead—the Father, the Son, and the Holy Ghost—is involved in the action required to make assurance to the human agent.”—Upward Look, 148.
All 3 members of the Godhead are eternal because they are each God.