This can be understood in two senses: whether children must obey their parents in the Lord, or whether children must obey their parents in the Lord. Both are necessary.
That is, we must obey those parents who begot us in the Lord, such as Paul and the other Apostles, and do what they command you. Likewise, we must obey in the Lord those parents from whom we were born according to the flesh, and do what is not contrary to God's will.
We shall also place the heretics in difficulty, who refuse to acknowledge that the Old Testament comes from the good God, whose Son is Jesus Christ. For this reason the Apostle of Christ, the Son of the good God, uses the Scripture of the Creator.
He borrows the teaching on the obedience of children from the Old Law. This testimony, taken from the Book of Exodus, is presented there in this form: "Honor your father and your mother, that it may be well with you, and that you may live long on the land which the Lord your God has given you" (Ex 20:12).
From this passage he has now omitted the final words. This is the fifth commandment of the Decalogue. Therefore one must ask why he says that this is the first commandment, when the first commandment says, "You shall have no other gods besides Me."
Because of this, some read it thus: "this is the first commandment with a promise," as though the first four commandments stated earlier contained no promises. According to them, only in this commandment is the promise set forth: "that it may be well with you, and that you may live long on the earth."
But it seems to me that these interpreters have not examined the commandments with sufficient care. A promise is joined to the second commandment. For it says: "You shall not make for yourself an idol, nor any likeness of what is above in heaven, or what is below on the earth, or what is in the waters under the earth."
"You shall not worship them or sacrifice to them. For I am the Lord your God, a jealous God, visiting the sins of the fathers upon the children to the third and fourth generation of those who hate Me. And I show mercy to many who love Me and carefully keep My commandments" (Ex 20:4-6).
Still, perhaps the Apostle spoke this way because, for the people coming out of Egypt, the Decalogue was the first law. Each commandment of the Decalogue should be called a first commandment in comparison with those later written in the Law.
Whoever holds to the interpretation mentioned above should say that the commandment is given separately here: "Honor your father and your mother." Afterward, in its own place, the promise is set down: "that you may live long on the land which the Lord your God has given you."
In that other commandment, "You shall not make for yourself an idol, nor any likeness," the promise is not given separately. In the same connection of words and discourse, it contains not so much a promise as a thought for praising God.
It praises Him as showing mercy to many who love Him and keep His commandments. On the other hand, one who seeks to prove that all the commandments of the Decalogue constitute the first commandment will argue that the promise of long life on the earth applies not only to those who obey parents, but also to many other commandments.
He will be compelled to present all the commandments in which the reward is set forth, namely, that those who fulfill them will live long on the land which the Lord God gave them.
But an interpreter who differs from him must demand proof that the commandments listed were written before this commandment. If he cannot prove this, then his assertion is vain, that a promise is also attached to other commandments.
After this, it must be shown that the promise of long life on earth to sons for honoring father and mother must not be understood in the Jewish, carnal sense. Indeed, it must be admitted that many who honored their parents died soon.
On the contrary, those who dishonored their parents sometimes reached very deep old age. If the promises speak of longevity, and if life in the body is happiness, then let the Jews and those like the Jews answer what the well-known passage in the Psalms means.
"Woe is me, that my sojourning has been prolonged. I dwelt with the inhabitants of Kedar" (Ps 119:5). And in the Ecclesiastes of Solomon there is this passage: "I praised all the dead, who have already died, more than the living, who are living until now."
"But better than both is he who has not yet been born and has not seen all the evil that has been done under the sun" (Eccl 4:2-3). And a little later: "If a man begets a hundred children and lives many years, and the days of his years are many, yet his soul is not satisfied with good things, and he has no burial, I still said: better than he is a miscarriage."
"For it came in vanity, and its name will be hidden in darkness, and it has not even seen the sun" (Eccl 6:3-5), and so on.
Indeed, if the dead are praised in comparison with the living, and, according to some who think that souls dwell in heaven before birth in bodies, if the one not yet born is better than both, then the whole of life is a trial.
According to Job, "Death is rest for a man" (Job 3:13). Likewise, according to him and according to Jeremiah, "Cursed is the day on which we are born" (Jer 20:14).
How, then, is it now promised to those who honor father and mother that they will live long on the land which the Lord their God gave them?
Therefore we must seek that land which the Lord promised and gave to those who departed from the spiritual Egyptian bondage. With all patience they passed through the dreadful deserts of this life.
They conquered many kings whom the Lord shook. They came to Judea, flowing with honey and milk. They destroyed Jericho under the leadership of Joshua and laid waste Ai, which means abyss.
They entered Jerusalem, and a temple was established for them under Solomon, the peaceful king (Josh 7). They received possession of the land prepared for the meek: "Blessed are the meek, for they shall inherit the earth" (Mt 5:5).
This is truly the land of the living, concerning which the Psalmist also says: "I believe that I shall see the good things of God in the land of the living" (Ps 26:13). He has long life and wisdom in his right hand, while holding riches and glory in his left.