Ephesians 1:13-14 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, (14) who is the guarantee of our inheritance until we acquire possession of it, to the praise of his glory.
At the moment of faith, believers are sealed with the promised indwelling of the Holy Spirit. This is a guarantee of the inheritance as adopted sons of the living God. The indwelling of God the Holy Spirit produces a changed human being that is a new creation in Christ. Believers are enabled to follow the lead of the Spirit due to the fulfillment of the new covenant promise of a new heart. This is new covenant grace and is the reason that the new covenant is much superior to the old covenant that it replaced.
Focus on Christ #102