Romans 14:17

17.For the kingdom of God, etc. He now, on the other hand, teaches us, that we can without loss abstain from the use of our liberty, because the kingdom of God does not consist in such things. Those things indeed, which are necessary either to build up or preserve the kingdom of God, are by no means to be neglected, whatever offenses may hence follow: but if for love’s sake it be lawful to abstain from meat, while God’s honor is uninjured, while Christ’s kingdom suffers no harm, while religion is not hindered, then they are not to be borne with, who for meat’s sake disturb the Church. He uses similar arguments in his first Epistle to the Corinthians:

“Meat,” he says, “for the stomach, and the stomach for meat; but God will destroy both,” (1 Corinthians 6:13 :)

again,

“If we eat, we shall not abound,” (1 Corinthians 8:8.)

By these words he meant briefly to show, that meat and drink were things too worthless, that on their account the course of the gospel should be impeded.

But righteousness and peace, etc. He, in passing, has set these in opposition to meat and drink; not for the purpose of enumerating all the things which constitute the kingdom of Christ, but of showing, that it consists of spiritual things. He has at the same time no doubt included in few words a summary of what it is; namely, that we, being well assured, have peace with God, and possess real joy of heart through the Holy Spirit dwelling in us. But as I have said, these few things he has accommodated to his present subject. He indeed who is become partaker of true righteousness, enjoys a great and an invaluable good, even a calm joy of conscience; and he who haspeace with God, what can he desire more? (430)

By connecting peace and joy together, he seems to me to express the character of this joy; for however torpid the reprobate may be, or however they may elevate themselves, yet the conscience is not rendered calm and joyful, except when it feels God to be pacified and propitious to it; and there is no solid joy but what proceeds from this peace. And though it was necessary, when mention was made of these things, that the Spirit should have been declared as the author; yet he meant in this place indirectly to oppose the Spirit to external things, that we might know, that the things which belong to the kingdom of God continue complete to us without the use of meats.