Bhagavad Gita 16.8असत्यमप्रतिष्ठं ते जगदाहुरनीश्वरम्।अपरस्परसम्भूतं किमन्यत्कामहैतुकम् ॥

They hold that the universe is without any substratum or support or an undying basic reality.This is a description of the opinion of atheists like the Charvakas and other materialists. They do not believe in the existence of Brahman Who is the support of this world. They do not even accept the existence of an Isvara in this world. They say We are unreal. Therefore this world also is unreal, the scriptures which declare the truth are also unreal. What else but lust can be the cause of this universe Sexual passion is the sole cause of all living creatures. There is no such thing as the theory of Karma. The whole world is caused by the mutual union of man and woman under the impulse of lust. There is neither virtue nor vice. There is no Lord Who dispenses the fruits of actions of the individuals according to virtue and vice. Dharma and Adharma are not the basis of this world. Sexual desire is the sole basis for this universe. This world is a world of chance. They are not endowed with the faculty of introspection. They are ignorant of the field (Nature) and knower of the field (God).Mutual union Sexual union it may mean the union of atoms. The world arose from the combination of atoms according to the Vaiseshikas.