The present age ... prefers the sign to the thing signified, the copy to the original, fancy to reality, the appearance to the essence ... for in these days illusion only is sacred, truth profane.

I have always taken as the standard of the mode of teaching and writing, not the abstract, particular, professional philosopher, but universal man, that I have regarded man as the criterion of truth, and not this or that founder of a system, and have from the first placed the highest excellence of the philosopher in this, that he abstains, both as a man and as an author, from the ostentation of philosophy, i. e., that he is a philosopher only in reality, not formally, that he is a quiet philosopher, not a loud and still less a brawling one.

For the religious the holy is truth, for the philosophic the truth is holy.

If therefore my work is negative, irreligious, atheistic, let it be remembered that atheism — at least in the sense of this work — is the secret of religion itself; that religion itself, not indeed on the surface, but fundamentally, not in intention or according to its own supposition, but in its heart, in its essence, believes in nothing else than the truth and divinity of human nature.

Only he is a truly ethical, a truly human being, who has the courage to see through his own religious feelings and needs.

Theology is Anthropology... [T]he distinction which is made, or rather supposed to be made, between the theological and anthropological predicates resolves itself into an absurdity.

To theology, ... only what it holds sacred is true, whereas to philosophy, only what holds true is sacred.