William Burkitt on Romans 14:18

He that in these things, that is, in righteousness, and peace, and joy in the Holy Ghost, serveth Christ, is acceptable to God. That is, this shows and evidences that he is a person accepted with God, and approved of men, of wise, charitable, and good men; yea, the natural consciences of men in general will applaud and approve what is done by him, notwithstanding the fore-mentioned difference in lesser things concerning meats and days.

Learn hence, That the love and practice of religious duties, such as righteousness and peace, is a clear and strong argument of a person's acceptance with God.

Learn, 2. That such as are for those things accepted by God, ought by no means, for differing from us in lesser things, to be disowned of us, and cast out of communion by us.