13 And you also were included in Christ when you heard the word of truth, the gospel of your salvation. Having 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.
We know that a certificate without official seal (or stamp) is not official and is not acceptable.
When we heard the gospel, we were included in Christ. When we believed, repented and got baptized, we were given this seal, the Holy Spirit.
How special to get a certificate by God saying that you are mine? What a privilege for us to know that our names are written in the book of life?
Remember the disciples who invited you and taught you the Bible. Pray for them and send an encouraging note to them. Thank God for the Holy Spirit in you, who is the seal of acceptance.