“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” (Ephesians 1:13).
Most careful commentaries of the Bible make it clear that the words “after listening,” in the above verse, actually have an immediate result in view. Upon hearing (or heeding), and upon believing, we are sealed with the Spirit.
What is perhaps even more important to note, is the fact that upon believing “the gospel of salvation,” we are sealed with the Holy Spirit, not just by the Holy Spirit. There is a difference between the two, which can be simply illustrated.
Imagine someone who is “putting up” honey or preserves and sealing each jar with wax. Now, the jars are being sealed by the individual, but they are sealing them with wax. Thus the Holy Spirit does not merely cause believers to be sealed and made secure. Rather He Himself is the Seal that keeps us eternally secure as God’s beloved children. We are sealed, not “by the Spirit,” but “with the Spirit,” … the Spirit Himself the Seal! source