God's promised Spirit seals us after we believe. Clearly, receiving the Holy Spirit is something that happened in our past. We received it upon faith, repentance, baptism, and the laying on of hands. Verse 14 clarifies that this occurred in the past, saying that what we received was merely an earnest, an installment guaranteeing that more will be given. The sense here is similar to Romans 8:32, where Paul writes that God's giving of His Son is our guarantee that He will withhold nothing that we truly need.
The word "until" in Ephesians 1:14 further clarifies the time-element by stating that this will not happen "until the redemption of the purchased possession" occurs. Have we assumed that we were redeemed when we believed, accepted Jesus Christ, and were justified by His blood? But, notice, Paul writes that this, too, is yet future!
There is a future reception of more of God's Holy Spirit and a future redemption! The Scripture cannot be broken (John 10:35). The apostle is teaching us that redemption, like salvation, is a process that has begun but has not yet reached its conclusion. Both of these processes began when we believed and accepted Jesus Christ, but they will not end until we receive God's Spirit in full measure and are glorified in His Kingdom.
Thus, just as we know that we do not now have God's Spirit in full measure, we have to realize that we are not yet fully redeemed. As used in the Bible, redeem means "to deliver one by means of paying a price." The price has been paid in full, and we are even now the recipients of merely the beginning of its blessings. In addition, it also places us under obligation to glorify God and show forth His praises, as we are able.
John W. Ritenbaugh
Our Uniqueness and Time