When we talk about liberation among the living i.e the jeevanmukts, is it their aatman which has achieved realization? If not the aatman, that what/who? For those who have done good karma in this birth and are guaranteed escape from the cycle of rebirth, what achieves moksha after loss of body/mind on death?
Yes. The Jivatma attains realization that it is part of Paramaatma. Technically, recognizing "Pratyabhijna" of one's true nature which is "akrtrima-aham-vimarsa" - the original, innate, pure I- consciousness.
Relevant scripture is "Siva sutras" Tantra I. Pg 192. and its commentary by Abhinav Gupta.
"Moksho he nama Nowanyahe swaroopaprathan he tatha"
Meaning, Moksha or liberation is nothing else but awareness of one's true nature.
The highest attainment is that of Siva-consciousness in which the entire universe appears as I or Siva and this comes by Saktipata - The descent of Divine Sakti or her grace Anugraha.
In order to attain Her grace there are four upayas (spiritual discipline) mentioned Anupaya, Sambhavopaya, Saktopaya and Anavopaya.
All Part of Kashmiri Shaivism and its excellent books.
Except Anupaya, the rest of the methods are spiritual discipline / Yoga one must have for attaining Moksha. The Siva Sutras cover the Yoga paths.
Anupaya is really interesting. It says that no description of it can be given. Sometimes, a guru tells a word and you get Self realization! It is sort of a "Reserved" part for knowledgable Gurus to induce Self-realization to an aspirant and is Gupt or secret.
Since, it is a secret you cannot find written descriptions of that.
To answer your second question, Good karmas are insufficient without Her Grace which in-turn means you should come under the category of any of the above Upayas.
The Yoga/Vedic path covers vidya ( Knowledge acquisition about Moksha and spiritual discipline) and avidya ( doing Nityakarmas, Yagna, Homas etc.) after doing all that you will be evaluated for Her grace to attain Moksha after you leave the body.
That covers the scripture descriptions.
But honestly and practically, How many people are thinking about re-birth and Moksha as they go about their daily activities except Monks who are dedicated? Let's pause and answer these questions
1) Why do you want Moksha?
If you say to chant the name of Lord for eternity then there are already a lot of souls who have attained Moksha doing exactly that. Of what use is your Moksha?
2) Shouldn't Monk's sacrifice and dedication warrant a Moksha?
Yes it should. However, without knowing the Real world which is run by Paramatma, How helpful will you be in running the World? Without full experience of the real world your knowledge level is insufficient to help Paramatma. That is the reason, Sanatana Dharma insisted on going through the stages of Life, starting with Brahmacharin, Grahastrama, Vanastashrama and on to become a real Saint and upon departure helps Paramatma in some way. Don't forget that the "Mayic" world that you see should continue to exist post your departure and certainly The Creator neither you would prefer to go back to "Darkness covered by Darkness" ( as per Nasadaya Sukta). For one thing that is really boring!
My two cents!
Moksha doesnot means disappearance of physical body from the physical world, that happens for the bound soul that is starting everything from zero in every birth with new set of parents, environment and everything. For Moksha/enlightenment is of the mind but neither of body nor Atman. What is Maya? Maya means ignorance, forgetfulness and inflated ego. Moksha means living in one cosmic consciousness Parbrahman Satchidananda Atman(one who has no Tamas and never sleeps/forgets) without hating and fighting others in the name of personal temporary ego and satisfaction for sensual pleasures. God/consciousness can be approached through several paths like Bhakti, Gyan and Karma Yoga etc.,. Thats what enlightened Purusha Krishna told to Arjuna.
Bhagavad Gita 4.4 Arjun said: You were born much after Vivasvan. How am I to understand that in the beginning you instructed this science to him?
Bhagavad Gita 4.5 The Supreme Lord said: Both you and I have had many births, O Arjun. You have forgotten them, while I remember them all, O Parantapa.
Bhagavad Gita 7.3 Amongst thousands of persons, hardly one strives for perfection; and amongst those who have achieved perfection, hardly one knows me in truth.
Thats why Krishna told Arjuna to do Bhakti of Saguna Brahman first to purify mind and Rama told the same thing to Hanuman. Muktika Upanishad
I-i-15-17. Hanuman: Rama, sages speak differently: some say there is only one kind of liberation. Others say it can be got by worshipping your name and by the Taraka mantra at Kashi. Others speak of Sankhya-Yoga and Bhakti-Yoga, the enquiry into Vedanta-Vakyas etc.
I-i-18-23. Rama: Liberation is of four kinds: Salokya, Sampeepya, Sarupya, Sayujya etc. But the only real type is Kaivalya. Anybody even though leading a wicked life, attains Salokya, not other worlds, by worshipping my name. Dying in the sacred Brahmanala in Kashi, he will get the Taraka-mantra and also liberation, without rebirth. On dying anywhere (else) in Kashi, Maheshvara will utter the Taraka-mantra in his right ear. He gets Sarupya with me as his sins are washed away.
The same is called Salokya and Sarupya. Persevering in good conduct, with mind fixed upon me, loving me as the Self of all, the twice-born gets nearer to me – This is called the three forms of liberation. Salokya, Sarupya and Samipya
I-i-26-29. But by what means is the Kaivalya kind of Moksha got ? The Mandukya is enough; if knowledge is not got from it, then study the Ten Upanishads. Getting knowledge very soon, you will reach my abode. If certainty is not got even then, study the 32 Upanishads and stop. If desiring Moksha without the body, read the 108 Upanishads.
I-i-40-43. These destroy three kinds of Bhavana (regarding) body, senses and mind respectively as identified with Atman. The best of Brahmanas will become Jivanmuktas if they study upto the destruction of Prarabdha, these 108 Upanishads from a Guru along with the Shanti-pada. Then, in course of time they will get Vedeha-mukti, surely.
Bound souls, worldly people, are like silkworms. They could come out of their cocoons if they wished, but they have built their own homes and maya does not allow them to escape. And it all ends with death. Liberated souls are not under the control of 'lust and greed'. Some clever silkworms cut their cocoons and come out.But they are very few. Because of maya (attachment), one remains forgetful. Few are not deluded by the magic of maya, are not subject to the control of 'lust and greed.' When the pot containing ashes from the maternity room falls on one's feet, the 'damn, damn' word of the magician can do no harm. One can see exactly what the magician is doing.
If you first fortify yourself with the true knowledge of the Universal Self, and then live in the midst of wealth and worldliness, surely they will in no way affect you.
But seek first his kingdom and his righteousness, and all these material things will be given to you as well.Whoever has the true knowledge will be given more, and they will have an abundance. Whoever does not have the truth, even what they have will be taken from them by death and forgetfulness