If Christianity can be proved to be a religion that inspires the love of God and man; yea, and the only religion in the world that does so; if it endues the mind of him that embraces it with a principle of justice, meekness, chastity, and goodness, and even gives a tone to the morals of society at large; it will then appear to carry its evidence along with it. The effects which it produces will be its letters of recommendation, written, “not with ink, but with the Spirit of the living God; not in tables of stone, but in fleshy tables of the heart.” Moreover, if Christianity can be proved to be in harmony with itself, correspondent with observation and experience, and consistent with the clearest dictates of sober reason, it will further appear to carry in it its own evidence; come through whose hands it may, it will evince itself to be what it professes to be—a religion from God.

I will only add, in this place, that the Christianity here defended is not Christianity as it is corrupted by popish superstition, or as interwoven with national establishments, for the accomplishment of secular purposes; but as it is taught in the New Testament, and practised by sincere Christians. There is no doubt but that, in many instances, Christianity has been adopted by worldly men, even by infidels themselves, for the purpose of promoting their political designs. Finding the bulk of the people inclined to the Christian religion under some particular form, and attached to certain leading persons among them who sustained the character of teachers, they have considered it as a piece of good policy to give this religion an establishment, and these teachers a share in the government. It is thus that religion, to its great dishonour, has been converted into an engine of state. The politician may be pleased with his success, and the teacher with his honours, and even the people be so far misled as to love to have it so; but the mischief resulting from it to religion is incalculable. Even where such establishments have arisen from piety, they have not failed to corrupt the minds of Christians from the simplicity which is in Christ. It was by these means that the church, at an early period, from being the bride of Christ, gradually degenerated to a harlot, and, in the end, became the mother of harlots, and abominations of the earth. The good that is done in such communities is not in consequence of their peculiar ecclesiastical constitution, but in spite of it; it arises from the virtue of individuals, which operates notwithstanding the disadvantages of their situation.

Excerpt: Andrew Fuller, The Gospel Its Own Witness; or, The Holy Nature and Divine Harmony of the Christian Religion Contrasted with the Immorality and Absurdity of Deism. 

Fuller, A. G. (1988). The Complete Works of Andrew Fuller: Controversial Publications. (J. Belcher, Ed.) (Vol. 2, p. 7). Harrisonburg, VA: Sprinkle Publications.