To deny all the qualities of a being is equivalent to denying the being itself. A being without qualities is one which cannot become an object to the mind, and such a being is virtually non-existent. To the truly religious man, God is not a being without qualities, because to him it is a positive, real being. The theory that God cannot be defined, and consequently cannot be known by man, is therefore the offspring of recent times, a product of modern unbelief.
The proposition that God is unknowable or undefinable, can only be enunciated and become fixed as a dogma, where this object has no longer any interest for the intellect; where the real, the positive, alone has any hold on man, where the real alone has for him the significance of the essential, of the absolute, divine object. On the ground that God is unknowable, man excuses himself to what is yet remaining of his religious conscience for his forgetfulness of God, his absorption in the world: he denies God practically by his conduct — the world has possession of all his thoughts and inclinations — but he does not deny it theoretically, he does not attack its existence; he lets that rest. But this existence does not affect or incommode him.
The denial of determinate, positive predicates concerning the divine nature is nothing else than a denial of religion; it is simply a subtle, disguised atheism. The alleged religious horror of limiting God by positive predicates is only the irreligious wish to know nothing more of God, to banish God from the mind.
Hence the position that there indeed is another, a heavenly life, but that what and how it is must here remain inscrutable, is only an invention of religious scepticism, which, being entirely alien to the religious sentiment, proceeds upon a total misconception of religion.
Ludwig Feuerbach – The Essence of Religion. The Christian heaven