As God's creatures, we are all debtors to Him: to obey Him with all our body and soul and strength. Having broken His commandments, as we all have, we are debtors to His justice, and we owe to Him a vast amount that we are not able to pay.
But of the Christian it can be said that he does not owe God's justice anything, for Christ has paid the debt His people owed; for this reason the believer is in debt to love. I am a debtor to God's grace and forgiving mercy; but I am no debtor to His justice, for He will never accuse me of a debt already paid. Christ said, "It is finished!" and by that He meant that whatever His people owed was wiped away forever from the book of remembrance. Christ has completely satisfied divine justice; the account is settled; the handwriting is nailed to the cross; the receipt is given, and we are no longer in debt to God's justice. But then it follows that since we are not debtors to our Lord in that sense, we become ten times more debtors to God than we should have been otherwise. Christian, pause and consider for a moment.
What a debtor you are to divine sovereignty! How much you owe to His disinterested love, for He gave His own Son that He might die for you.
Consider how much you owe to His forgiving grace, that even after ten thousand offenses He loves you as infinitely as ever.
Consider what you owe to His power; how He has raised you from your death in sin; how He has preserved your spiritual life; how He has kept you from falling; and how, though a thousand enemies have surrounded your path, you have been able to hold on your way.
Consider what you owe to His immutability. Though you have changed a thousand times, He has not changed once.
You are as deep in debt as you can be to every attribute of God. To God you owe yourself and all you have: Offer yourself as a living sacrifice; it is but your reasonable service.