From the book King of knowledge, Chapter Four, by Prabhupada.

The mūḍhas, or foolish men, who are lower than the animals, deride Him. Any person who doesn’t believe in God must either be a madman or fool number one. There is no reason not to believe in God, and there is every reason to believe in Him. Man may say that he doesn’t believe in God, but who gives him the power to say this? When death comes, this speaking power ceases—so who is giving the power of speech? Has the speaking power come automatically from stone? As soon as the speaking power is withdrawn by the Supreme Authority, the body is no better than stone. The very power of speech is proof that there is a Supreme Power who is giving us everything. A Kṛṣṇa conscious person knows that whatever he has is not under his control. If we do not believe in God, we must believe in some power beyond us which is controlling us at every step, call that power God or nature or whatever. There is a controlling power in the universe, and no sane man can deny it. ~ from the book king of knowledge, Chapter Four, by Prabhupada.