What does the Bible say about the sealing of the Spirit?

In 2 Corinthians 1:21-22, Paul writes about God establishing and anointing believers, sealing them with the Spirit as a guarantee of their inheritance. This sealing serves to assure Christians of their full acceptance and adoption as children of God. The presence of the Spirit in our hearts acts as an earnest, signifying that we are God’s own, thus alleviating doubts and fears regarding our salvation. The sealing of the Spirit is a sign of God's commitment to His people, offering a deep sense of assurance and confidence in their relationship with Him.