Meanwhile in Europe, a revolutionary meets Marx and Proudhon and becomes a different type of anarchist. Like Warren and Proudhon, he held the normative labor-value dogma, but his critique of state is articulate and blistering enough to warm the hearts of anarchists everywhere. Like Spooner, Bakunin was a freethinker. Bakunin rejected God as an affront to human dignity and liberty.
If God is, he is necessarily the eternal, supreme, absolute master, and, if such a master exists, man is a slave; now, if he is a slave, neither justice, nor equality, nor fraternity, nor prosperity are possible for him. In vain, flying in the face of good sense and all the teachings of history, do they represent their God as animated by the tenderest love of human liberty: a master, whoever he may be and however liberal he may desire to show himself, remains none the less always a master. His existence necessarily implies the slavery of all that is beneath him. Therefore, if God existed, only in one way could he serve human liberty - by ceasing to exist.
Also like Spooner, Bakunin recognized the existence of natural law. He defines liberty as the recognition of these laws by an uncoerced mind.
A jealous lover of human liberty, and deeming it the absolute condition of all that we admire and respect in humanity, I reverse the phrase of Voltaire, and say that, if God really existed, it would be necessary to abolish him. - Michael Bakunin, God and the State (1871)
In his relation to natural laws but one liberty is possible to man - that of recognizing and applying them on an ever-extending scale in conformity with the object of collective and individual emancipation or humanization which he pursues. These laws, once recognized, exercise an authority which is never disputed by the mass of men. ...
The liberty of man consists solely in this: that he obeys natural laws because he has himself recognized them as such, and not because they have been externally imposed upon him by any extrinsic will whatever, divine or human, collective or individual. - Michael Bakunin, God and the State