"At present only a small portion of the knowledge contained in the Vedas, Vedānta-sūtra, and Upaniṣads is available to the general populace. What is noteworthy, however, is that the essence of all Vedic knowledge is available in the Gītopaniṣad, popularly known as the Bhagavad-gītā. Lord Kṛṣṇa milked the cow of the Upaniṣads, and Arjuna drank the milk thus obtained—the Bhagavad-gītā. If Arjuna found time to hear the Bhagavad-gītā in the middle of a battlefield at Kuruksetra, then what urgent business is stopping us from hearing the Gītā? When knowledge of the Gītā spreads, then everyone will easily be able to attain the platform of yoga. And as the pure devotees
of the Lord become successful in their efforts to use their spiritual intelligence in the Lord's service, then the science of love of God taught by Lord Caitanya, the most magnanimous incarnation of Godhead, will be distributed everywhere. Judging from all the symptoms, the time is now ripe. Indians should now take shelter of their saintly preceptors, the pure devotees, and unitedly propagate the glorification of Kṛṣṇa via the medium of the Bhagavad-gītā. In this way the world will become prosperous and perfect."
Renunciation Through Wisdom 5.1
Here is an excerpt by A.C. Bhaktivedanta Swami Prabhupada, the greatest exponent of Bhagavad Gita in the modern time.
"If one reads Bhagavad-gita very sincerely and with all seriousness, then by the grace of the Lord the reactions of his past misdeeds will not act upon him." (Gita-mahatmya 2)
The Lord says very loudly in the last portion of Bhagavad-gita (18.66):
"Abandon all varieties of religion and just surrender unto Me. I shall deliver you from all sinful reactions. Do not fear." Thus the Lord takes all responsibility for one who surrenders unto Him, and He indemnifies such a person against all reactions of sins.”
"One may cleanse himself daily by taking a bath in water, but if one takes a bath even once in the sacred Ganges water of Bhagavad-gita, for him the dirt of material life is altogether vanquished." (Gita-mahatmya 3)
Because Bhagavad-gita is spoken by the Supreme Personality of Godhead, one need not read any other Vedic literature. One need only attentively and regularly hear and read Bhagavad-gita. In the present age, people are so absorbed in mundane activities that it is not possible for them to read all the Vedic literatures. But this is not necessary. This one book, Bhagavad-gita, will suffice, because it is the essence of all Vedic literatures and especially because it is spoken by the Supreme Personality of Godhead. (Gita-mahatmya 4)
"One who drinks the water of the Ganges attains salvation, so what to speak of one who drinks the nectar of Bhagavad-gita? Bhagavad-gita is the essential nectar of the Mahabharata, and it is spoken by Lord Krsna Himself, the original Visnu."
Bhagavad-gita comes from the mouth of the Supreme Personality of Godhead, and the Ganges is said to emanate from the lotus feet of the Lord. Of course, there is no difference between the mouth and the feet of the Supreme Lord, but from an impartial study we can appreciate that Bhagavad-gita is even more important than the water of the Ganges. Gita-mahatmya 6)
"This Gitopanisad, Bhagavad-gita, the essence of all the Upanisads, is just like a cow, and Lord Krsna, who is famous as a cowherd boy, is milking this cow. Arjuna is just like a calf, and learned scholars and pure devotees are to drink the nectarean milk of Bhagavad-gita." ((Gita-mahatmya 7)
In this present day, people are very much eager to have one scripture, one God, one religion, and one occupation. Therefore, ekam sastram devaki-putra-gitam: let there be one scripture only, one common scripture for the whole world-Bhagavad-gita. Eko devo devaki-putra eva: let there be one God for the whole world-Sri Krsna. Eko mantras tasya namani: and one hymn, one mantra, one prayer -- the chanting of His name: Hare Krsna, Hare Krsna, Krsna Krsna, Hare Hare/ Hare Rama, Hare Rama, Rama Rama, Hare Hare. Karmapy ekam tasya devasya seva: and let there be one work only -- the service of the Supreme Personality of Godhead.