What is Mukthi (liberation)?
It is not the attainment of a heavenly abode. Mukthi means freedom from suffering. For example, you are hungry. When you eat food, your hunger is satiated. This is a kind of Mukthi. Say, you are suffering from a disease. You take medicine and get cured. This is also Mukthi. All this is related to the body. At the mental level, Mukthi means controlling the vagaries of the mind. But true liberation lies in understanding the principle of the Atma which neither comes nor goes.
Liberation (Mukthi) can simply be defined as freedom from the material consciousness, resulting in dissolving of the instinctive mind or false ego — death from the bondage, Maya or repeated pain and suffering in a physical body. That is to say, to attain a blessed state of the Jeevanmukta is to overcome mental delusion and recover one's Divine Identity as Pure Consciousness. Hence to attain perfect liberation while living, Realization of the Self needs to be brought through into every aspect of life and every atom of the body.
An ordinary mortal or a conditioned soul is continuously stirred up by Maya (illusion, ignorance, false ego, mistaken identity, delusion, etc.) while witnessing his day-to-day life. But a Jeevanmukta observes the play of the life through the prism of the Pure Consciousness — without any desires, emotional attachment, restlessness, prejudices and agitations of the mind. The teachings of the world scriptures are intended to awaken this Pure Consciousness within. This Unconditioned Consciousness is our true nature, which can be awakened by fully roasting the seed of ignorance in the fire of Self-knowledge (Aatam-Gian).
What is Atma?
The real Self, one's Divinity. God, the substance of everything, the spark of God within. The Atma is unchanging, immortal. Atman (Sanskrit) "The soul; the breath; the principle of life and sensation." The soul in its entirety - as the soul body (anandamaya kosha) and its essence (Parashakti and Parasiva). One of Hinduism's most fundamental tenets is that we are the atman, not the physical body, emotions, external mind or personality.