Question: "What is the seal of the Holy Spirit?"
Answer: The Holy Spirit is referred to as the “deposit,” “seal,” and “earnest” in the hearts of Christians (2 Corinthians 1:22; 5:5; Ephesians 1:13-14; 4:30). The Holy Spirit is God’s seal on His people, His claim on us as His very own. The Greek word translated “earnest” in these passages is arrhabōn which means “a pledge,” that is, part of the purchase money or property given in advance as security for the rest. The gift of the Spirit to believers is a down payment on our heavenly inheritance, which Christ has promised us and secured for us at the cross. It is because the Spirit has sealed us that we are assured of our salvation. No one can break the seal of God.
The Holy Spirit is given to believers as a “first installment” to assure us that our full inheritance as children of God will be delivered. The Holy Spirit is given to us to confirm to us that we belong to God who grants to us His Spirit as a gift, just as grace and faith are gifts (Ephesians 2:8-9). Through the gift of the Spirit, God renews and sanctifies us. He produces in our hearts those feelings, hopes, and desires which are evidence that we are accepted by God, that we are regarded as His adopted children, that our hope is genuine, and that our redemption and salvation are sure in the same way that a seal guarantees a will or an agreement. God grants to us His Holy Spirit as the certain pledge that we are His forever and shall be saved in the last day. The proof of the Spirit’s presence is His operations on the heart which produce repentance, the fruit of the Spirit (Galatians 5:22-23), conformity to God’s commands and will, a passion for prayer and praise, and love for His people. These things are the evidences that the Holy Spirit has renewed the heart and that the Christian is sealed for the day of redemption.
So it is through the Holy Spirit and His teachings and guiding power that we are sealed and confirmed until the day of redemption, complete and free from the corruption of sin and the grave. Because we have the seal of the Spirit in our hearts, we can live joyfully, confident of our sure place in a future that holds unimaginable glories.