“Of all the animosities which have existed among mankind, those which are caused by difference of sentiments in religion appear to be the most inveterate and distressing, and ought most to be deprecated.”

Book IV, Ch. 18
An Essay Concerning Human Understanding (1689)

As quoted in Essays on Freedom and Power, Introduction, p. xlvii (1949) https://mises.org/sites/default/files/Essays%20on%20Freedom%20and%20Power_3.pdf

Source: The Wealth of Nations (1776), Book IV, Chapter II

Oration at Plymouth (1802)
Context: Among the sentiments of most powerful operation upon the human heart, and most highly honorable to the human character, are those of veneration for our forefathers, and of love for our posterity. They form the connecting links between the selfish and the social passions. By the fundamental principle of Christianity, the happiness of the individual is Later-woven, by innumerable and imperceptible ties, with that of his contemporaries: by the power of filial reverence and parental affection, individual existence is extended beyond the limits of individual life, and the happiness of every age is chained in mutual dependence upon that of every other.

The First Part, Chapter 12, p. 54
Leviathan (1651)

Letter of Constantine to the Antiochians (332)
Constantine the Great : Letters
Context: How pleasing to the wise and intelligent portion of mankind is the concord which exists among you! And I myself, brethren, am disposed to love you with an enduring affection, inspired both by religion, and by your own manner of life and zeal on my behalf. It is by the exercise of right understanding and sound discretion, that we are enabled really to enjoy our blessings... Indeed, amongst brethren, whom the selfsame disposition to walk in the ways of truth and righteousness promises, through the favor of God, to register among his pure and holy family, what can be more honorable than gladly to acquiesce in the prosperity of all men?... O holy faith, who givest us in our Saviour's words and precepts a model, as it were, of what our life should be, how hardly wouldst thou thyself resist the sins of men, were it not that thou refusest to subserve the purposes of gain! In my own judgment, he whose first object is the maintenance of peace, seems to be superior to Victory herself; and where a right and honorable course lies open to one's choice, surely no one would hesitate to adopt it. I ask then, brethren, why do we so decide as to inflict an injury on others by our choice? Why do we covet those objects which will destroy the credit of our own reputation?... Lastly, in accordance with your usual sound judgment, do ye exhibit a becoming diligence in selecting the person of whom you stand in need, carefully avoiding all factious and tumultuous clamor; for such clamor is always wrong, and from the collision of discordant elements both sparks and flame will arise. I protest, as I desire to please God and you, and to enjoy a happiness commensurate with your kind wishes, that I love you, and the quiet haven of your gentleness, now that you have cast from you that which defiled, and received in its place at once sound morality and concord, firmly planting in the vessel the sacred standard, and guided, as one may say, by a helm of iron in your course onward to the light of heaven.

Essay on the Principle of Population (1798; rev. through 1826)

Letter to William B. Giles (26 December 1825)
1820s
Context: An opinion prevails that there is no longer any distinction, that the republicans & Federalists are completely amalgamated but it is not so. The amalgamation is of name only, not of principle. All indeed call themselves by the name of Republicans, because that of Federalists was extinguished in the battle of New Orleans. But the truth is that finding that monarchy is a desperate wish in this country, they rally to the point which they think next best, a consolidated government. Their aim is now therefore to break down the rights reserved by the constitution to the states as a bulwark against that consolidation, the fear of which produced the whole of the opposition to the constitution at its birth. Hence new Republicans in Congress, preaching the doctrines of the old Federalists, and the new nick-names of Ultras and Radicals. But I trust they will fail under the new, as the old name, and that the friends of the real constitution and union will prevail against consolidation, as they have done against monarchism. I scarcely know myself which is most to be deprecated, a consolidation, or dissolution of the states. The horrors of both are beyond the reach of human foresight.