Newmans sermon "Knowledge of Gods Will without Obedience" reflects on the words of Christ: "If ye know these things, happy are ye if ye do them" (Jn 13:17).

Now, doubtless, many of us think we know this very well. It seems a very trite thing to say, that it is nothing to know what is right, unless we do it; an old subject about which nothing new can be said. When we read such passages in Scripture, we pass over them as admitting them without dispute; and thus we contrive practically to forget them. Knowledge is nothing compared with doing; but the knowing that knowledge is nothing, we make to be something, we make it count, and thus we cheat ourselves.This we do in parallel cases also. Many a man instead of learning humility in practice, confesses himself a poor sinner, and next prides himself upon the confession; he ascribes the glory of his redemption to God, and then becomes in a manner proud that he is redeemed. He is proud of his so-called humility.Doubtless Christ spoke no words in vain. The Eternal Wisdom of God did not utter His voice that we might at once catch up His words in an irreverent manner, think we understand them at a glance, and pass them over. But His word endureth for ever; it has a depth of meaning suited to all times and places, and hardly and painfully to be understood in any. They, who think they enter into it easily, may be quite sure they do not enter into it at all.

A little further on, he has this:

Is it not so? is not Scripture altogether pleasant except in its strictness? do not we try to persuade ourselves, that to feel religiously, to confess our love of religion, and to be able to talk of religion, will stand in the place of careful obedience, of that self-denial which is the very substance of true practical religion?

Here is his second portrait of people who claim to know without obeying:

Take again another description of them. They have perhaps turned their attention to the means of promoting the happiness of their fellow-creatures, and have formed a system of morality and religion of their own; then they come to Scripture. They are much struck with the high tone of its precepts, and the beauty of its teaching. It is true, they find many things in it which they do not understand or do not approve; many things they would not have said themselves. But they pass these by; they fancy that these do not apply to the present day, (which is an easy way of removing any thing we do not like,) and on the whole they receive the Bible, and they think it highly serviceable for the lower classes. Therefore, they recommend it, and support the institutions which are the channels of teaching it. But as to their own case, it never comes into their minds to apply its precepts seriously to themselves; they know them already, they consider. They know them and that is enough; but as for doing them, by which I mean, going forward to obey them, with an unaffected earnestness and an honest faith acting upon them, receiving them as they are, and not as their own previously formed opinions would have them be, they have nothing of this right spirit. They do not contemplate such a mode of acting. To recommend and affect a moral and decent conduct (on whatever principles) seems to them to be enough. The spread of knowledge bringing in its train a selfish temperance, a selfish peaceableness, a selfish benevolence, the morality of expedience, this satisfies them. They linecare for none of the truths of Scripture, on the ground of their being in Scripture; these scarcely become more valuable in their eyes for being there written. They do not obey because they are told to obey, on faith; and the need of this divine principle of conduct they do not comprehend. Why will it not answer (they seem to say) to make men good in one way as well as another? "Abana and Pharpar, rivers of Damascus, are they not better than all the waters of Israel?" [see 2 Kings 5:12], as if all the knowledge and the training that books ever gave had power to unloose one sinner from the bonds of Satan, or to effect more than an outward reformation, an appearance of obedience; as if it were not a far different principle, a principle independent of knowledge, above it and before it, which leads to real obedience, that principle of divine faith, given from above, which has life in itself, and has power really to use knowledge to the soul's welfare; in the hand of which knowledge is (as it were) the torch lighting us on our way, but not teaching or strengthening us to walk.