Romans 14:20

20.All things are indeed pure, etc. By saying, that all things are pure, he makes a general declaration; and by adding, that it is evil for man to eat with offense, he makes an exception; as though he had said, — “Meat is indeed good, but to give offense is bad.” Now meat has been given to us, that we may eat it, provided love be observed: he then pollutes the use of pure meat, who by it violates love. Hence he concludes, that it is good to abstain from all things which tend to give offense to our brethren.

He mentions three things in order, to fall, to stumble, to be weakened: the meaning seems to be this, — “Let no cause of falling, no, nor of stumbling, no, nor of weakening, be given to the brethren.” For to be weakened is less than to stumble, and to stumble is less than to fall. He may be said to be weakened whose conscience wavers with doubt, — to stumble when the conscience is disturbed by some greater perplexity, and to fall when the individual is in a manner alienated from his attention to religion. (433)