Found just three times in the New Testament (2 Cor. 1:22; 5:5; Eph. 1:14), the Greek noun “arrhabon” meant “earnest,” “pledge,” “deposit.”

Paul used this term to say the Holy Spirit serves as an “earnest” or “pledge” for the saved.  In some way or sense the Holy Spirit serves as a “promise” that the saved are truly part of the redeemed (compare Acts 2:38).  Unsaved people might be regarded as having the mark of the devil, but the saved have “the pledge of the Spirit.”  This fact may be related to verses like Rev. 22:4b.