Now Yama organizes the bodily functions in a hierarchy. He says, “Higher than the senses are the sense objects. Higher than the sense objects is the mind. Reason or buddhi is higher than the mind. The mahat or awareness is higher than buddhi. Higher than the mahat is avyakta, undifferentiated nature. The infinite Self, purusa is greater than avyakta and the purusa is the supreme goal. There is nothing higher than This.”
Purusa is an alternate name for Brahman or Atman. 

Now Yama introduces the imagery of the chariot. “The atman is the master of the chariot and the body is the chariot. Know the intellect, buddhi as the charioteer and the mind manas as the reins. The sense organs, they say, are the horses and the sense objects are roads they travel over. They call the atman the “enjoyer” or “experiencer” when It is united with the body, senses and the mind.
The imagery of the chariot is also used by Plato in his Phaedrus but the usage there is different. Plato’s chariot has only two horses and we leave it to the reader to discern how it differs from Yama’s chariot.
Yama continues, “For him who is devoid of understanding, with a mind not disciplined, the sense organs become uncontrolled like the unruly horses of the chariot. He does not reach the goal but returns to the world of birth and death again. But he who has proper understanding, mind under control, ever pure, reaches the goal.” 

Discovering the atman in every being, the wise become immortal.

the Kena Upanishad compels us to inquire how it is that we perceive anything. It confronts us with fundamental questions about the mys- tery of perception and finally indicates the mystery of ourselves. It concludes by saying that mystery is Brahman. It cannot be said to be known since we cannot objectify It. Nor can it be said to be unknown since we experience It every moment, nay, It is the cause of our experience. Thus It is more than the known and the unknown. 

The wise who separate the atman from the sensory functions become immortal.
The eye cannot approach It, neither speech nor mind. We do not therefore know It, nor do we know how to teach It. It is different from what is known and It is beyond what is unknown. Thus we have heard from our teachers who taught us
I do not think I know It well. Nor do I think that I do not know It. He knows It who knows that It is other than the unknown and the known. The teacher’s reply is the following. He knows who knows It not. He knows It not who knows. It is unknown to the one who knows. It is known to the one who does not know. 

there is no god

There is no God separate from you, no God higher than you, the real 'you'. All the gods are little beings to you, all the ideas of God and Father in heaven are but your own reflection. God Himself is your image. 'God created man after His own image.' That is wrong. Man creates God after his own image. That is right. Throughout the universe we are creating gods after our own image. We create the god and fall down at his feet and worship him; and when this dream comes, we love it!” - Vivekananda