by 
I will be their God, and they will be my people (Hebrews 8:10b).
The second promise of the New Covenant is this:
I will be their God, and they will be my people.
This is a declaration from God. There are no strings attached. There are no hoops to jump through, no ladders of behavior to climb. God simply declared “I will be their God, and they will be my people.”
This is not an “if/then” proposition. In the Old Covenant, God said “IF you obey my statutes and commandments, THEN I will be your God.”
No, in this New Covenant, when God marks you as his own, then you are his forever.
Listen to Paul’s words to the Ephesians…
And 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, who is a deposit guaranteeing our inheritance until the redemption of those who are God’s possession—to the praise of his glory (Ephesians 1:13, 14).
Jesus is the deposit guaranteeing your eternal inheritance. Your heart’s response is one of thankfulness.
So today, give thanks.
You belong to the King of Kings.
You have been marked out as one of his very own.
And that is good news.
Remember this verse: “When you believed, you were marked in him with a seal, the promised Holy Spirit”. You have been marked and sealed eternally as one of God’s own children. There is nothing that you can do to break that seal. That’s assurance.
In Him,
Bob Christopher