The book recognized as containing the most complete attempt at explaining and defending pantheism from a philosophical perspective is Spinoza's Ethic… - Benedictus de Spinoza

In the state of nature, wrong-doing is impossible ; or, if anyone does wrong, it is to himself, not to another. For no one by the law of nature is bound to please another, unless he chooses, nor to hold anything to be good or evil, but what he himself, according to his own temperament, pronounces to be so ; and, to speak generally, nothing is forbidden by the law of nature, except what is beyond everyone's power.

When you say Spinoza, however, besides being too flattering, the comparison is not biographically so true. My Spinozism is in the Life of Reason, less obviously, perhaps, yet more dominantly, than in Realms of Being. These, as you know, are not at all like Spinoza's attributes. They are not aspects or forms of the same reality, absolutely parallel and coextensive. My realms are layers: more as in Plotinus; and my moral or “spiritual” philosophy is again less Spinozistic than in the humanistic period. Spinoza's moral sentiments were plebeian, Dutch, and Jewish: perfectly happy in his corner, polishing his lenses, and saying, Great is Allah. No art, no high politics, no sympathy with greatness, no understanding of courage or of despair.

We know that Spinoza's metaphysics remained widely influential throughout the eighteenth century. A philosopher who received five times more attention than Descartes or Locke in Bayle's Dictionnaire, Diderot and J. d'Alembert's Encyclopédie, and Zedler's Grosses Universal Lexikon was certainly not ignored by the Enlightenment – indeed, could not be.