Regarding Spinoza, whom M. Arnauld has called the most impious and most dangerous man of this century, he was truly an Atheist, [i.e.,] he allowed ab… - Benedictus de Spinoza

...Since, in consequence of the Kantian criticism of all speculative theology, the philosophisers of Germany almost all threw themselves back upon Spinoza, so that the whole series of futile attempts known by the name of the post-Kantian philosophy are simply Spinozism tastelessly dressed up, veiled in all kinds of unintelligible language, and otherwise distorted, I wish, now that I have explained the relation of my philosophy to Pantheism in general, to point out its relation to Spinozism in particular. It stands, then, to Spinozism as the New Testament stands to the Old. What the Old Testament has in common with the New is the same God-Creator. Analogous to this, the world exists, with me as with Spinoza, by its inner power and through itself. But with Spinoza his substantia æterna, the inner nature of the world, which he himself calls God, is also, as regards its moral character and worth, Jehovah, the God-Creator, who applauds His own creation, and finds that all is very good, παντα καλα λιαν. Spinoza has deprived Him of nothing but personality. Thus, according to him also, the world and all in it is wholly excellent and as it ought to be: therefore man has nothing more to do than vivere, agere, suum Esse conservare ex fundamento proprium utile quærendi (Eth., iv. pr. 67); he is even to rejoice in his life as long as it lasts; entirely in accordance with Ecclesiastes ix. 7-10. In short, it is optimism: therefore its ethical side is weak, as in the Old Testament; nay, it is even false, and in part revolting. With me, on the other hand, the will, or the inner nature of the world, is by no means Jehovah, it is rather, as it were, the crucified Saviour, or the crucified thief, according as it resolves. Therefore my ethical teaching agrees with that of Christianity, completely and in its highest tendencies, and not less with that of Brahmanism and Buddhism. Spinoza could not get rid of the Jews; quo semel est imbuta recens servabit odorem. His contempt for the brutes, which, as mere things for our use, he also declares to be without rights, is thoroughly Jewish, and, in union with Pantheism, is at the same time absurd and detestable (Eth., iv., appendix, c. 27). With all this Spinoza remains a very great man. But in order to estimate his work correctly we must keep in view his relation to Descartes.

Spinoza, then, emerged as the supreme philosophical bogeyman of Early Enlightenment Europe. Admittedly, historians have rarely emphasized this. It has been much more common, and still is, to claim that Spinoza was rarely understood and had very little influence, a typical example of an abiding historiographical refrain which appears to be totally untrue but nevertheless, since the nineteenth century, has exerted an enduring appeal for all manner of scholars. In fact, no one else during the century 1650–1750 remotely rivalled Spinoza's notoriety as the chief challenger of the fundamentals of revealed religion, received ideas, tradition, morality, and what was everywhere regarded, in absolutist and non-absolutist states alike, as divinely constituted political authority.

“He who loves God,” Spinoza says, “cannot strive that God should love him in return.” Goethe, in a passage of characteristic sentimentality, misquotes this proposition in singling it out for special praise; he quotes it as, “Who loves God truly must not expect God to love him in return,” and regards it as an example of “Entsagen sollst du, sollst entsagen.” If Goethe had understood Spinoza's religion, he would not have made this mistake. Spinoza, here and elsewhere, is not inculcating resignation; he himself loved what he judged to be best, and lived, so far as one can discover, without effort in the way which he held to be conformable to reason. There seems to have been in him, what his philosophy was intended to produce in others, an absence of bad desires; hence, his nature is harmonious and gentle, free from the cruelty of asceticism, or the monkishness of the cloister, or the moralistic priggery of Goethe's praises.