Explanation:

The Aatmasamyama Yoga is mentioned in the Gita, which means that the self should be controlled. Here the self means the inert energy which is the basic form of awareness. This is the first and final step for atheists. This step is essential for the Nivrutti Yoga also because the self or inert energy is to be diverted for the divine work. Therefore, the Atma Yoga is common for both atheists and theists. The atheists stop in Atma Yoga itself and attain happiness by getting liberation from the expenditure of self in worldly issues. For an atheist, the attainment of self or inert energy reducing the activities of awareness is the end. The self is God for him and hence, Shankara used the word Brahman sounding God to mean the self. Here Brahman (God) means the ultimate goal.

Any ultimate goal, beyond which the journey is stopped, can be called as God. A guardian for a boy is said to be the godfather. Here the guardian is neither God nor father. It only means that the guardian is the ultimate. But for a theist, this Atma Yoga is only a preparatory ground for the real spiritual effort. His goal is not the self present in the human body. His goal is God. But God is also present in a specific human being like Shankara, Vasudeva etc. Since God exists in a self, the self could also mean the medium in which God is present. For him, the Atma Yoga means the attainment of God in human form. The meaning of the word Atman or self should be carefully understood as per the context. For example, in the Gita, it is said that the self should uplift the self (Uddharedatmanaatmanam…). The first self means the contemporary human incarnation of God and the second self means the ordinary human being who is trying to spiritually uplift himself. A soul cannot uplift itself and also cannot be uplifted by any other soul. Only God in the form of a soul like Vasudeva or Shankara can uplift any soul. The theist gets infinite happiness from God whereas an atheist gets finite happiness from self-attainment or Atma Yoga as per the Gita (Vindantyamani yatsukham…, Sukhamakshayamashnute…). Thus, the word Atman is also double edged like the word Brahman.