Albert Barnes on Romans 14:18

In these things. In righteousness, peace, and joy.

Serveth Christ. Or obeys Christ, who has commanded them. He receives Christ as his Master or Teacher, and does his will in regard to them. To do these things is to do honour to Christ, and to show the excellency of his religion.

Is acceptable to God. Whether he be converted from the Jews or the Gentiles.

And approved of men. That is, men will approve of such conduct; they will esteem it to be right, and to be in accordance with the spirit of Christianity. He does not say that the wicked world will love such a life, but it will commend itself to them as such a life as men ought to lead.