Ephesians 1:13-14 NIVUK
13 …you also were included in Christ when you heard the message of truth, the gospel of your salvation. When you believed, you were marked in him with a seal, the promised Holy Spirit, 14 who is a deposit guaranteeing our inheritance until the redemption of those who are God’s possession—to the praise of his glory.

When I married Kate, she and I exchanged wedding rings as a symbol of our marriage, to show that we belong to each other. The same is happening here. When we enter a relationship with God, he marks us with a symbol or seal to show that we belong to each other, the Holy Spirit who lives in us. His presence and work in our lives is proof our our being accepted and loved by God.

Father, thank you for the wonderful relationship we have with you!