"In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise, Which is the earnest of our inheritance until the redemption of the purchased possession, unto the praise of His glory" (Ephesians 1:13-14).
From very ancient times it has been the custom to confirm and guarantee an agreed-on purchase by sealing the contract with a seal which could only be broken by the buyer when he was ready to take possession of his purchase.
The marvelous transaction seen by John at God's throne in heaven was in reference to this practice. There, only the Lamb is found worthy to open the seven-sealed scroll on which is recorded the title to the whole creation. "And they sung a new song, saying, Thou art worthy to take the [scroll], and to open the seals thereof: for thou wast slain, and hast redeemed us to God by thy blood" (Revelation 5:9). The purchase price had been paid on Calvary, and the resurrected Lamb had come to claim His possession.
And we are part of that possession! The price has been paid for our redemption from sin's bondage, but we have not yet entered on the inheritance which our great Redeemer has promised us. In the meantime, our individual title deed, as it were, has been sealed by none other than the Holy Spirit. He is not only the seal, but also the "earnest" -- that is, the down payment, the earnest money -- who guarantees the total "redemption of the purchased possession."
His personal presence in our lives is our assurance that the full promise will be fulfilled, and we are urged to "grieve not the holy Spirit of God, whereby ye are sealed unto the day of redemption" (Ephesians 4:30). He "hath also sealed us, and given the earnest of the Spirit in our hearts" (II Cor-inthians 1:22). HMM