Gibbon on ancient religion

The policy of the emperors and the senate, as far as it concerned religion, was happily seconded by the reflections of the enlightened, and by the habits of the superstitious, part of their subjects. The various modes of worship, which prevailed in the Roman world, were all considered by the people, as equally true; by the philosopher, as equally false; and by the magistrate, as equally useful. And thus toleration produced not only mutual indulgence, but even religious concord.

The superstition of the people was not imbittered by any mixture of theological rancour; nor was it confined by the chains of any speculative system. The devout polytheist, though fondly attached to his national rites, admitted with implicit faith the different religions of the earth. ….. A republic of gods of such opposite tempers and interests required, in every system, the moderating hand of a supreme magistrate, who, by the progress of knowledge and flattery, was gradually invested with the sublime perfections of an Eternal Parent, and an Omnipotent Monarch.  Such was the mild spirit of antiquity, that the nations were less attentive to the difference, than to the resemblance, of their religious worship. The Greek, the Roman, and the Barbarian, as they met before their respective altars, easily persuaded themselves, that under various names, and with various ceremonies, they adored the same deities.  The elegant mythology of Homer gave a beautiful, and almost a regular form, to the polytheism of the ancient world.

The philosophers of Greece deduced their morals from the nature of man, rather than from that of God.

Prefigures Robespierre, Salin, Hitler and Franco

An anxious regard to his personal safety was the ruling principle of the administration of Valens. In the condition of a subject, he had kissed, with trembling awe, the hand of the oppressor; and when he ascended the throne, he reasonably expected, that the same fears, which had subdued his own mind, would secure the patient submission of his people. The favourites of Valens obtained, by the privilege of rapine and confiscation, the wealth which his economy would have refused.  They urged, with persuasive eloquence, that, in all cases of treason, suspicion is equivalent to proof; that the power supposes the intention, of mischief; that the intention is not less criminal than the act; and that a subject no longer deserves to live, if his life may threaten the safety, or disturb the repose, of his sovereign. The judgment of Valentinian was sometimes deceived, and his confidence abused; but he would have silenced the informers with a contemptuous smile, had they presumed to alarm his fortitude by the sound of danger. They praised his inflexible love of justice; and, in the pursuit of justice, the emperor was easily tempted to consider clemency as a weakness, and passion as a virtue. As long as he wrestled with his equals, in the bold competition of an active and ambitious life, Valentinian was seldom injured, and never insulted, with impunity: if his prudence was arraigned, his spirit was applauded; and the proudest and most powerful generals were apprehensive of provoking the resentment of a fearless soldier. After he became master of the world, he unfortunately forgot, that where no resistance can be made, no courage can be exerted; and instead of consulting the dictates of reason and magnanimity, he indulged the furious emotions of his temper, at a time when they were disgraceful to himself, and fatal to the defenceless objects of his displeasure. In the government of his household, or of his empire, slight, or even imaginary, offences—a hasty word, a casual omission, an involuntary delay—were chastised by a sentence of immediate death.