It is indeed a most lamentable consequence of the practice of regarding religion as a compilation of statutes, and not as an internal principle, that it soon comes to be considered as being conversant about external actions, rather than about habits of mind. This sentiment sometimes has even the hardiness to insinuate and maintain itself under the guise of extraordinary concern for practical religion; but it soon discovers the falsehood of this pretension, and betrays its real nature. The expedient indeed of attaining to superiority in practice, by not wasting any of the attention on the internal principles from which alone practice can flow, is about as reasonable, and will answer about as well, as the economy of the architect who should account it mere prodigality to expend any of his materials in laying foundations, from an idea that they might be more usefully applied to the raising of the superstructure. We know what would be the fate of such an edifice.

It is indeed true, and a truth never to be forgotten, that all pretensions to internal principles of holiness are vain, when they are contradicted by the conduct; but it is no less true, that the only effectual way of improving the latter, is by a vigilant attention to the former. It was therefore our blessed Savior’s injunction, “Make the tree good” as the necessary means of obtaining good fruit; and the holy Scriptures abound in admonitions, to let it be our chief business to cultivate our hearts with all diligence, to examine into their state with impartiality, and watch over them with continual care. Indeed it is the heart which constitutes the man; and external actions derive their whole character and meaning from the motives and dispositions of which they are the indications. . . .

Yet though this be a truth so obvious, so established, that to have insisted on it may seem almost needless; it is a truth of which we are apt to lose sight in the review of our religious character, and with which the habit of considering religion as consisting rather in external actions than internal principles, is at direct and open war

Another excerpt from William Wilberforce, A Practical View of the Prevailing Religious System of Professed Christians in the Higher and Middle Classes of This Country Contrasted With Real Christianity (1797). The book is available in its entirety at the link. Here is a three-page pdf file of this excerpt, plus last week’s excerpt plus surrounding text. Note that, as was common in his day, when Wilberforce uses the word “religion,” he most often is referring solely to Christianity.