What does the Bible mean by being sealed with the Holy Spirit?

The concept of being sealed with the Holy Spirit points to a believer's secure standing before God. As stated in Ephesians 1:13-14, believers are sealed with the Holy Spirit of promise, which is the guarantee of our inheritance until the redemption of the purchased possession. This seal illustrates God's ownership over us and serves as a mark of authenticity and security in our salvation. It assures believers of God’s continual presence and the eventual fulfillment of His eternal promises, emphasizing the importance of the Holy Spirit's work in every aspect of the believer's life.