And he that doubteth. — The one thing which justifies a man in neglecting such nice and punctilious distinctions is a faith so strong that it can afford to make light of them. Where faith is not strong enough for this, and where the conscience deliberately approves one course, and the other course is chosen, this alone stamps the act as wrong. “He who hesitates as to what he ought to do is condemned, or does wrong, if he eats (in opposition to his conscience), for he has not the one faculty which can overrule the decisions of conscience, and give them a different direction.”
Whatsoever is not of faith is sin. — This is intended as a general principle, but only as a general principle covering this particular kind of case. Where the conscience is in doubt, faith alone can make it right to choose the side against which conscience inclines. Nothing is said about those cases in which conscience is either not appealed to at all, or approves what is done. Hence St. Augustine was wrong in arguing from this passage that even good actions, when done by unbelievers, were of the nature of sin.