If we only consider religious institutions in a purely human point of view, they may be said to derive an inexhaustible element of strength from man himself, since they belong to one of the constituent principles of human nature.
I am aware that at certain times religion may strengthen this influence, which originates in itself, by the artificial power of the laws, and by the support of those temporal institutions which direct society.
Religions, intimately united to the governments of the earth, have been known to exercise a sovereign authority derived from the twofold source of terror and of faith; but when a religion contracts an alliance of this nature, I do not hesitate to affirm that it commits the same error as a man who should sacrifice his future to his present welfare; and in obtaining a power to which it has no claim, it risks that authority which is rightfully its own.

When a religion founds its empire upon the desire of immortality which lives in every human heart, it may aspire to universal dominion; but when it connects itself with a government, it must necessarily adopt maxims which are only applicable to certain nations.

Thus, in forming an alliance with a political power, religion augments its authority over a few, and forfeits the hope of reigning over all.
As long as a religion rests upon those sentiments which are the consolation of all affliction, it may attract the affections of mankind.
But if it be mixed up with the bitter passions of the world, it may be constrained to defend allies whom its interests, and not the principle of love, have given to it; or to repel as antagonists men who are still attached to its own spirit, however opposed they may be to the powers to which it is allied.

The Church cannot share the temporal power of the State without being the object of a portion of that animosity which the latter excites.
The political powers which seem to be most firmly established have frequently no better guarantee for their duration than the opinions of a generation, the interests of the time, or the life of an individual.
A law may modify the social condition which seems to be most fixed and determinate; and with the social condition everything else must change.
The powers of society are more or less fugitive, like the years which we spend upon the earth; they succeed each other with rapidity, like the fleeting cares of life; and no government has ever yet been founded upon an invariable disposition of the human heart, or upon an imperishable interest.
As long as a religion is sustained by those feelings, propensities, and passions which are found to occur under the same forms, at all the different periods of history, it may defy the efforts of time; or at least it can only be destroyed by another religion.

But when religion clings to the interests of the world, it becomes almost as fragile a thing as the powers of earth.