We say, the śāstra says, that by chanting Hare Kṛṣṇa mantra, you become cleansed of your sinful activities. That's a fact. But if somebody thinks that, "I shall go on committing sinful activities and chant Hare Kṛṣṇa mantra so it will be adjusted, neutralized," this is the most sinful activity. Nāmno balāt, by the strength of chanting, committing sin. So similarly, on the strength of Bhagavad-gītā if one wants to prove his foolish philosophy, that is a great offense. That's a great offense.
Therefore Bhagavad-gītā cannot be interpreted by foolish commentators. It must be studied through the paramparā system, ācārya upāsanam. One must worship the ācārya and learn from him what is Bhagavad-gītā. Ācāryavān puruṣo veda (Chāndogya Upaniṣad 6.14.2)—this is the Vedic injunction—who knows things as they are. Ācāryaṁ māṁ puruṣa, one who is under the guidance of ācārya. So you won't find this foolish nonviolence theory from any ācārya. Many ācāryas have commented on Bhagavad-gītā—there is Rāmānujācārya, Madhvācārya, even Śaṅkarācārya—but never said that Bhagavad-gītā is proof of nonviolence. Nonviolence is good, but when there is dharma-yuddha, righteous fighting, there is no question of nonviolence. Violence is approved.