Bhagavad-gītā has to be understood. In the Fourth Chapter you find out that,
This is paramparā. The truth of Bhagavad-gītā was first spoken to the sun god, and he spoke to his son, to Manu, Vaivasvata Manu. And Vaivasvata Manu spoke to his son, Ikṣvāku. And Kṛṣṇa said, evaṁ paramparā-prāptam imaṁ rājarṣayo viduḥ (BG 4.2). Rājarṣaya. This philosophy of Bhagavad-gītā, it is meant for the rājarṣi, not for the loafer class. Rājarṣi: king, at the same time, saintly person. Imaṁ rājarṣayo viduḥ. Kṛṣṇa does not say that ordinary scholar or so-called philosopher can understand. Only the rājarṣayo viduḥ. So Arjuna is one of the rājarṣis. So he understood Kṛṣṇa. He says, he says, paraṁ brahma paraṁ dhāma (BG 10.12). So we have to accept this paramparā system. If we take Bhagavad-gītā seriously, then we should follow the footprints of Arjuna as he understood. He accepted Kṛṣṇa as the Paraṁbrahman. So what is spoken by Paraṁbrahman, the Supreme Lord, the Supreme Person, how we can interpret His words and squeeze out some meaning and mislead myself and mislead others? This is not good.
So our this Kṛṣṇa consciousness movement is trying to rectify this mistake. Bhagavad-gītā is the most authorized scripture in the Vedic literature. Vedic literature means it is not spoken by any ordinary human being. Apaureṣaya means this literature, Vedic literature, is spoken directly by the Supreme Person, or Lord. So it was instructed through Brahmā, Lord Brahmā.