Charles Hodge on Ephesians 6:1

V. 1. Children, obey your parents. The nature or character of this obedience, is expressed by the words, in the Lord. It should be religious; arising out of the conviction that such obedience is the will of the Lord. This makes it a higher service than if rendered from fear or from mere natural affection. It secures its being prompt, cordial and universal. That Κύριος here refers to Christ is plain from the whole context. In the preceding chapter, v. 21, we have the general exhortation under which this special direction to children is included, and the obedience there required is to be rendered in the fear of Christ. In the following verses also Κύριος constantly has this reference, and therefore must have it here. The ground of the obligation to filial obedience is expressed in the words, for this is right. It is not because of the personal character of the parent, nor because of his kindness, nor on the ground of expediency, but because it is right; an obligation arising out of the nature of the relation between parents and children, and which must exist wherever the relation itself exists.