What does it mean that whatever is not of faith is sin (Romans 14:23)?

“Hast thou faith? have it to thyself before God.” Faith must be an intensely personal thing. To press my faith on another would be virtually to do away with his exercise of faith. If I am before God, then let each individual saint be also before God. I cannot expect to be happy if I am judged in the thing that I allow. He that doubts is judged if he eats because it is not with the full liberty of personal faith that he eats. If we have any real concern for our brother we shall wholeheartedly seek to have him act only in faith. “For whatsoever is not of faith is sin.” It is a solemn, sweeping statement. Sin is not merely in the outward acts of men, but in everything in which faith does not have part. Shall we dare thus to virtually make our brother sin?

Practically, peace and edification are to be the great aim in all these debatable points. If thou hast faith, instead of doubts, so much the better, but have it to thyself before God. Blessed is he who does not judge himself in what he allows, (or approves,) but he who doubts is condemned if he eat, because it is not from faith; but whatsoever is not from faith is sin: that is, whatever is not done in liberty of faith.

God intends us to be exercised as to such matters, each for himself. Were there a definite command in Scripture there need not be the exercise. Then, simple obedience is the only course pleasing to God. But these other matters, how many they are. Should I go here or there? Should I partake of this or that? May I enjoy this pleasurable recreation or not? Ought we to carry out this service or this ordinance in this way or that way? What acrimonious and harmful controversies have raged around such questions. And the answer is so simple. Let the wrangling cease! Hands off each other! Each man to his own knees, in the presence of his own Master, that he may get, as far as in him lies, the knowledge of his Master's will.

Having settled in the Master's presence what we believe He would have us do, let us do it in the simplicity of faith. Only it must tee faith, and not self-will. And we must not go beyond or lag behind our faith. To do this is to bring condemnation (not, damnation) into our consciences, as the last two verses of the chapter tell us.

I do not examine minutely the remaining verses. The reiteration of the principle (verses 20, 21) attests its intrinsic importance in the eye of the Spirit of God. But in verse 22 we are furnished with a decisive test by which genuine spiritual liberty may be at all times distinguished from its counterfeit, carnal wilfulness. "Hast thou faith? Have it to thyself before God." There is a careless assumption of privilege, founded on doctrinal liberty, which is quite a different thing from faith. The faith here spoken of is a fruit of the Spirit (Gal. 5:22). It is not justifying faith in Christ, but it is a fruit which grows and results as a practical effect of the justified believer's personal communion with the Lord. This faith is a home joy of the soul. It abides within, choosing the privacy of the presence it loves best (Prov. 5:15-19). Faith of this kind courts no observation, and makes no boast of privilege. It is discovered in its effects, and these effects are always according to God, and therefore for blessing to others. The light and liberty enjoyed within may enable one thus blessed to help forward with more effect the lagging steps of those who need some guide to clear them, it may be, from the mazy ground in which they are bewildered. Meanwhile, it is the heart's pure peace and blessedness to be thus fully filled with Christ.

But there is another point connected with this. The presence of God is the only place where faith can really act. But God is light. And in that light is everything to be weighed before it is allowed under the plea of liberty. Conscience thus becomes the regulator, as it were, of faith. Else mere persuasion of self-will might easily usurp the place of genuine faith toward God. And so it is added: "Happy is he that condemns not himself in the thing that he alloweth." A weighty sentence, and full of needed caution, such as may temper and regulate the flow of Christian liberty, lest, ceasing to be restrained within the conscious limits of godly fear, it should degenerate to mere self-pleasing, and the natural license of the fleshly will.

The last verse of the chapter states another principle of still more solemn importance. A Christian is a man of faith. If he ever walks according to a lower principle, he is dishonouring, so far, the standing which he occupies. Nothing that a Christian does is merely indifferent. It is an act either of obedience or of sin: that is, he is either pleasing God or himself. Hesitation or doubt as to any course, is a peremptory reason for abstaining from it. The moment there is a question as to the nature or quality of a step proposed, the question is already decided in the heart of faith. For faith can go nowhere without God. Actions which do not satisfy the conscience before Him are always wrong. God leads in the way of uprightness. The light which He is is radiated through the word into the heart that lives upon Him. The consideration of the large amount of action in which a saint may be engaged, with, perhaps, no thought at all as to its true nature or intent, is a truly solemn one when taken in the light of this passage.

Have we faith to do certain things, let us have it before God. To be strong in faith is right, but we are not to attempt to lead another to do something about which he is doubtful. It may lead him into a path which is not of faith; and whatsoever cannot be done in faith is sin.