In Him, you also, after listening to the message of truth, the gospel of your salvation – having also believed, you were sealed in Him with the Holy Spirit of promise. – Ephesians 1:13
The last phrase of this verse says that we are “sealed in Him with the Holy Spirit of promise.” This verse is talking about the fact that the Holy Spirit is in us, and we sense Him in us and with us. The Spirit’s very presence is the promise that God began something in you when He saved you. Furthermore, it is the assurance that He is going to complete the work He started all the way to glorification. You will make it to heaven. And I would challenge you with very strong and clear admonition; make sure you sense the Spirit of God alive in your soul! It is the seal, the authentication, the mark that you are God’s.
There are two sides to this coin. One way the Spirit’s sealing is manifested is the conviction of sin. Sin troubles you differently. Sin humbles you. You have a new capacity to be brutally honest with yourself and truly mean it when you think you are the chief of sinners.
Secondly, the word of God begins to become alive to you. I’m not saying every day, but you have noticed that since the time you were born again, you find yourself learning and loving the Word like never before. Whether it’s the revealing of sin or the glorious assurances of the saving power of Christ, you find the Spirit within you strongly confirming the teaching of the word of God! There is something in you that wants more of the Word! That something in you is the Spirit of God! I call this strong confirming sense the “amen” of the Spirit.
This is the key part of the sealing work of the Spirit!