The ideal of the supreme being is nothing but a regulative principle of reason which directs us to look upon all connection in the world as if it originated from an all-sufficient necessary cause.
The perfect mystic is not an ecstatic devotee lost in contemplation of Oneness, nor a saintly recluse shunning all commerce with mankind, but "the true saint" goes in and out amongst the people and eats and sleeps with them and buys and sells in the market and marries and takes part in social intercourse, and never forgets God for a single moment.
Those thinkers who cannot believe in any gods often assert that the love of humanity would be in itself sufficient for them; and so, perhaps, it would, if they had it.