The fourth chapter of the Bhagavad Gita is Jnana Karma Sanyasa Yoga. In this chapter, Krishna glorifies the Karma Yoga and imparts the Transcendental Knowledge (the knowledge of the soul and the Ultimate Truth) to Arjuna. He reveals the reason behind his appearance in this material world. He reveals that even though he is eternal, he reincarnates time after time to re-establish dharma and peace on this Earth. His births and activities are eternal and are never contaminated by material flaws. Those persons who know and understand this Truth engage in his devotion with full faith and eventually attain Him. They do not have to take birth in this world again.
Indeed, there is nothing purifying here comparable to Knowledge. One who has become perfected after a (long) time through yoga, realizes That by himself in his own heart.OPEN VERSE
The man who has faith, is diligent and has control over the organs, attains Knowledge. Achieving Knowledge, one soon attains supreme Peace.OPEN VERSE
One who is ignorant and faithless, and has a doubting mind perishes. Neither this world nor the next nor happiness exists for one who has a doubting mind.OPEN VERSE
O Dhananjaya (Arjuna), actions do not bind one who has renounced actions through yoga, whose doubt has been fully dispelled by Knowledge, and who is not inadvertent.OPEN VERSE
Therefore, O scion of the Bharata dyasty, take recourse to yoga and rise up, cutting asunder with the sword of Knowledge this doubt of your own in the heart, arising from ignorance.OPEN VERSE