David Hume, answered from the texts and cited to the page.
Two related lines of argument run through the philosophy of religion. On miracles: a miracle is by definition a violation of the laws of nature, which laws are established by uniform experience. The proof against any particular miracle is therefore as complete as any argument from experience can be. The proof for it must rest on testimony, and the credit of testimony is itself an empirical matter, calibrated by experience.
No testimony is sufficient to establish a miracle unless the testimony be of such a kind that its falsehood would be more miraculous than the fact it endeavors to establish.1 This standard is virtually never met. On natural theology: the design argument infers from apparent design in nature to a designing intelligence. The Dialogues, modeled on Cicero, work systematically through the difficulties.
The analogy is weak: human design produces artifacts of bounded scale, while the universe is unbounded. The argument proves at most that the cause or causes of order in the universe bear some remote analogy to human intelligence — not that they are infinite, perfect, single, or moral. The problem of evil compounds the difficulty: from the world we observe, we cannot infer a benevolent omnipotent designer.
The Natural History of Religion completes the picture: the historical development of religion is a sociological process driven by fear, hope, and the human propensity to anthropomorphize, not a progression toward theological truth.234
But in order to encrease the probability against the testimony of witnesses, let us suppose, that the fact, which they affirm, instead of being only marvellous, is really miraculous; and suppose also, that the testimony considered apart and in itself, amounts to an entire proof; in that case, there is proof against proof, of which the strongest must prevail, but still with a diminution of its force, in proportion to…An Enquiry Concerning Human Understanding, p. 32
Nor would any of human race merit his favour, but a very few, the philosophical Theists, who entertain, or rather indeed endeavour to entertain, suitable notions of his Divine perfections: As the only persons entitled to his compassion and indulgence would be the philosophical Sceptics, a sect almost equally rare, who, from a natural diffidence of their own capacity, suspend, or endeavour to suspend, all judgement…Dialogues Concerning Natural Religion, p. 16
In the infancy of new religions, the wise and learned commonly esteem the matter too inconsiderable to deserve their attention or regard. And when afterwards they would willingly detect the cheat, in order to undeceive the deluded multitude, the season is now past, and the records and witnesses, which might clear up the matter, have perished beyond recovery.An Enquiry Concerning Human Understanding, p. 33
Thus you may judge of the Candor of the whole Charge, when you see the assigning of one Kind of Evidence for a Proposition, instead of another, is called denying that Proposition; that the invalidating only one Kind of Argument for the Divine Existence is called positive Atheism; nay, that the weakning only of one individual Argument of that Kind is called rejecting that whole Species of Argument, and…A Treatise of Human Nature, pp. 427–428
The foundational sustained critique of natural theology in modern philosophy. The miracles essay structures contemporary epistemology of testimony in religion (J.L. Mackie's The Miracle of Theism extends it; John Earman's Hume's Abject Failure attempts a Bayesian refutation). The Dialogues remain the most influential single work of philosophy of religion since Aquinas. The contemporary debate runs between defenders of natural theology (Richard Swinburne's Bayesian design argument, William Lane Craig's kalam revival) and Hume-line critics (Mackie, Sober, the broadly secular philosophy of religion mainstream). Plantinga's reformed epistemology is a different kind of response, sidestepping natural theology entirely. The Dialogues' structural argument against design has not been displaced.