In Him you also trusted, after you heard the word of truth, the gospel of your salvation; in whom also, having believed, you were sealed with the Holy Spirit of promise, who is the guarantee of our inheritance until the redemption of the purchased possession, to the praise of His glory. (Eph 1:13-14 NKJ)

In biblical times, a seal was a guarantee. Ephesians 1:13-14 Paul writes regarding the Holy Spirit, “In him you also, when you heard the word of truth, the gospel of your salvation, and believed in him, were sealed with the promised Holy Spirit, who is the guarantee of our inheritance until we acquire possession of it, to the praise of his glory.” According to this passage, the seal of the Holy Spirit takes place at the point of salvation. It is a promise or guarantee of the Christian’s future, eternal inheritance with Jesus Christ.

The Greek word translated as “seal” is shragizo that means “to set a seal upon, mark with a seal.”

1. The Holy Spirit in the believer’s life helps to guarantee he or she is a child of God. “The Spirit himself bears witness with our spirit that we are children of God.” (Romans 8:16)
2. The seal of the Holy Spirit serves as a mark that we actually belong to Christ. “You, however, are not in the flesh but in the Spirit, if in fact, the Spirit of God dwells in you. Anyone who does not have the Spirit of Christ does not belong to him. (Romans 8:9-10)
3. The seal of the Holy Spirit helps protect against tampering or attack. “For if you live according to the flesh you will die, but if by the Spirit you put to death the deeds of the body, you will live.” (Romans 8:13)