What is absolute knowledge? How can this knowledge help in attaining 
Devotion to God? What happens to one who is devoid of this knowledge?
Jnana refers to knowledge of self as distinguished from non self, or in other words, knowledge that the spirit soul is not the body. Vijnana refers to specific knowledge of the spirit soul’s constitutional position and his relationship to the Supreme Soul. It is explained thus in the Srimad Bhagavatam (2.9.31):
jnanam parama guhyam me
yadvijnana samanvitam
sa rahasyam tad angam ca
“The knowledge of the self and Supreme Self is very confidential and mysterious, but such knowledge and specific realization can be understood if explained with their various aspects by the Lord Himself.” Bhagavad gita gives us that general and specific knowledge of the self. The living entities are parts and parcels of the Lord, and therefore they are simply meant to serve the Lord. This consciousness is called Krishna consciousness. So, from the very beginning of life one has to learn this Krishna consciousness, and thereby one may become fully Krishna conscious and act accordingly. Gita 3.41, purport)
“He is knowledge, He is the object of knowledge, and He is the goal of knowledge. He is situated in everyone’s heart.” (Gita 13.18)
Empirical knowledge overcoated with devotional service is called jnana yoga. (Bhagavatam 1.2.15, purport)

Jnana Yoga Jnana Yogi And The Ignorant

Jnana yoga is the process of liberation from the material conditions. (Bhagavatam 2.2.12, purport)
The jnana yoga system aims at the impersonal Brahman effulgence. (Bhagavatam 3.25.29, purport)
The group of transcendentalists who follow the path of the inconceivable, unmanifested, impersonal feature of the Supreme Lord are called jnana yogis. (Gita 12.5, purport)
The jnana process theoretically speculates about the reality of the soul. (Bhagavatam 1.18.26, purport)
A sannyasi, or one in the renounced order of life, must be situated in fearlessness, sattva samsuddhi (purity) and jnana yoga (knowledge). (Gita 16.1–3, purport)
As far as jnanis are concerned, they are interested in jnana yoga, but even if one elevates oneself, after a great performance of austerity, to the Brahman effulgence, there is a chance of falling down again to the material world. Therefore, jnana yoga does not actually end material existence. (Bhagavatam 3.25.29, purport)
Udara dhih means one who has a broader outlook. People with desires for material enjoyment worship small demigods, and such intelligence is condemned in the Bhagavad gita (7.20) as hrta jnana, the intelligence of one who has lost his senses. (Bhagavatam 2.3.10, purport)
1. Most sublime: “Even if you are considered to be the most sinful of all sinners, when you are situated in the boat of transcendental knowledge you will be able to cross over the ocean of miseries.” Proper understanding of one’s constitutional position in relationship to Krishna is so nice that it can at once lift one from the struggle for existence which goes on in the ocean of nescience. This material world is sometimes regarded as an ocean of nescience and sometimes as a blazing forest. In the ocean, however expert a swimmer one may be, the struggle for existence is very severe. If someone comes forward and lifts the struggling swimmer from the ocean, he is the greatest savior. Perfect knowledge, received from the Supreme Personality of Godhead, is the path of liberation. The boat of Krishna consciousness is very simple, but at the same time the most sublime. (Gita 4.36, translation and purport)
2. Acts like fire: “As a blazing fire turns firewood to ashes, O Arjuna, so does the fire of knowledge burn to ashes all reactions to material activities.” Perfect knowledge of self and Superself and of their relationship is compared herein to fire. This fire not only burns up all reactions to impious activities, but also all reactions to pious activities, turning them to ashes. There are many stages of reaction: reaction in the making, reaction fructifying, reaction already achieved, and reaction a priori. But knowledge of the constitutional position of the living entity burns everything to ashes. When one is in complete knowledge, all reactions, both apriori and a posteriori, are consumed. (Gita 4.37, translation and purport)
“O chastiser of the enemy, the sacrifice performed in knowledge is better than the mere sacrifice of material possessions. After all, O son of Prtha, all sacrifices of work culminate in transcendental knowledge.” Depending on differences in consciousness, sacrificial activities are sometimes called karma kanda (fruitive activities) and sometimes jnana kanda (knowledge in the pursuit of truth). It is better when the end is knowledge. (Gita 4.33, translation and purport)
Direct Krishna consciousness is bhakti yoga, and jnana yoga is a path leading to bhakti yoga. Krishna consciousness means to work in full knowledge of one’s relationship with the Supreme Absolute, and the perfection of this consciousness is full knowledge of Krishna, or the Supreme Personality of Godhead. (Gita 5.29, purport)
Knowledge is always highly esteemed. And what is that knowledge? Perfect knowledge is achieved when one surrenders unto Krishna, as is said in Bhagavad gita (7.19): bahunam janmanam ante jnanavan mam prapadyate. After passing through many, many births, when one perfect in knowledge surrenders unto Krishna, or when one attains Krishna consciousness, then everything is revealed to him, as everything is revealed by the sun in the daytime. (Gita 5.16, purport)
“To those who are constantly devoted to serving Me with love, I give the understanding by which they can come to Me. To show them special mercy, I, dwelling in their hearts, destroy with the shining lamp of knowledge the darkness born of ignorance.” (Gita 10.10–11, translation)
“One is understood to be in full knowledge whose every endeavor is devoid of desire for sense gratification. He is said by sages to be a worker for whom the reactions of work have been burned up by the fire of perfect knowledge.” (Gita 4.19)

Kali Yuga Sea of Faults

“The work of a man who is unattached to the modes of material nature and who is fully situated in transcendental knowledge merges entirely into transcendence.” (Gita 4.23)
When he knows that the goal is Krishna but he takes pleasure in mental speculations to understand Krishna, he is acting in jnana yoga. (Gita 10.10, purport)
One who follows the instruction of the Bhagavad gita, as it is imparted by the Lord, the Personality of Godhead Himself, becomes free from all doubts by the grace of transcendental knowledge. He, as a part and parcel of the Lord, in full Krishna consciousness, is already established in self knowledge. As such, he is undoubtedly above bondage to action. (Gita 4.41, purport)
One whose mind, intelligence, faith, and refuge are always in Krishna, or, in other words, one who is fully in Krishna consciousness, is undoubtedly washed clean of all misgivings and is in perfect knowledge in everything concerning transcendence. A Krishna conscious person can thoroughly understand that there is duality (simultaneous identity and individuality) in Krishna, and, equipped with such transcendental knowledge, one can make steady progress on the path of liberation. (Gita 5.17, purport)
Those who see with eyes of knowledge the difference between the body and the knower of the body, and can also understand the process of liberation from bondage in material nature, attain to the supreme goal. (Gita 13.35)
Jnana (or knowledge that one is not this material body but spirit soul) is not sufficient for liberation. One has to act in the status of spirit soul; otherwise there is no escape from material bondage. (Gita 5.2, purport)
After one is liberated from the conditions of material existence, i.e., when one is nivritta, as previously stated herein, or when one is freed from all material necessities, one becomes qualified to discharge the process of bhakti yoga. (Srimad Bhagavatam 2.2.12, purport)