You serve the Lord Christ

“And whatever you do, work heartily, as for the Lord, and not for men, knowing that from the Lord you will receive the reward of the inheritance; for you serve the Lord Christ.”
—Colossians 3:23,24

“As to the Lord, and not as to men. It sanctifies a servant’s work when it is done as unto God— with an eye to his glory and in obedience to his command, and not merely as unto men, or with regard to them only. Observe, We are really doing our duty to God when we are faithful in our duty to men. And, for servants’ encouragement, let them know that a good and faithful servant is never the further from heaven for his being a servant: “Knowing that of the Lord you shall receive the reward of the inheritance, for you serve the Lord Christ, v. 24. Serving your masters according to the command of Christ, you serve Christ, and he will be your paymaster: you will have a glorious reward at last. Though you are now servants, you will receive the inheritance of sons.”
— Matthew Henry