Prabhupāda: In any religious system, the killing of animal there is. In every religious system, there is. But why there is this killing of a living entity? It is not good. But why in the religious system there is permission for killing animal? So that is explained. The explanation is that a person who is a staunch meat-eater, he cannot give up meat-eating, so . . . at the same time he wants to be religious. This is the position. So for such person it is enjoined, just like in Vedic system, "All right, if you want to eat meat, at the same time you want to become religious, then you worship Goddess Kālī. You cannot worship Viṣṇu." Because he's a meat-eater, he cannot approach pavitraṁ paramaṁ bhavān. The Supreme Personality is the supreme pure. So this meat-eater is impure. He cannot approach the pure. That is not possible. Therefore he is advised to approach some agent of the pure, some śakti, or just like Goddess Kālī. Goddess Kālī is the śakti, or the agent, potency. Kālī has got also business: to cut the heads of the demons. You have seen the Goddess Kālī's picture, muṇḍa-mālā. She's garlanded with the heads of the demons. Have you seen? Any one of you?
Devotee (3): I have seen kālī-pūjā.
Prabhupāda: Yes. But her business is to cut off the heads of the demons. She is carrying one head in this hand, and in this hand she's carrying a chopper, and her business is to cut the heads of the demons. But she's also the agent of the Supreme Personality of Godhead. How she's agent? Because God has got two business: paritrāṇāya sādhūnāṁ vināśāya ca duṣkṛtām (BG 4.8). Duṣkṛtino mūḍhāḥ, narādhamāḥ, māyayāpahṛta-jñānā āsuraṁ bhāvam āśritāḥ (BG 7.15). For them the Goddess Kālī is engaged to cut their heads, kill them. That is also Kṛṣṇa's agent.