Kṛṣṇa supported the Battle of Kurukṣetra, it was not whimsical declaration of war. Before declaring war, Pāṇḍavas, even Kṛṣṇa tried to stop it in so many ways. When Duryodhana clearly said that "Not even that portion of land which can hold the tip of a needle can be given to you without war . . ." They were . . . Kṛṣṇa personally requested that "They are kṣatriyas.
They cannot take up the work of a brahmin or a śūdra or a vaiśya. So better you give them five villages only. Let the five brothers rule over them." He replied: "What do You say of five villages? Not that portion of land which can hold the tip of a needle I can give them without war." Therefore the war was declared: "All right. Decide by war." That was not a whimsical war manufactured and maneuvered by the politician. That is dharma-yuddha. When you encroach upon my right, there must be. Tena tyaktena bhuñjīthā mā gṛdhaḥ kasya svid dhanam (ISO 1). You cannot encroach upon others' right.
So the animal killer, they are encroaching upon others' right. This cows and goats, they are also living entities; they have got right to live. When there is absolute necessity, that is a different thing. But you cannot encroach upon their right of living simply to satisfy the taste of your tongue. That is the greatest sin. Similarly, illicit sex. One has got wife and he is having illicit sex with other woman, that is . . . that is crime. "You want to satisfy your sex? All right. You have got legitimate wife." "No. I want to satisfy my senses." Therefore illicit sex is sinful. You have got many other foodstuff. Why should you satisfy your senses by killing some other right of living?
Therefore it is . . . why it is sinful, anyone can understand. Just like if I have no money, that does not mean to secure money I shall take your money. Then I am thief. You cannot say: "Oh, I have no money. This man has got so much money, therefore I have taken some money." Will the court excuse you? Even if you have no food, you cannot encroach upon other's right unless you are sanctioned.