According to Vedic system one is married, and married means the girl has got a husband and the boy has got a wife. So living on religious principles, they can satisfy their sex life for begetting nice children. So there is no prohibition. That is allowed. But illicit sex means your attachment for sex is increased, not for Kṛṣṇa. Therefore it is forbidden.
No meat-eating. Meat-eating or fish-eating or egg-eating, non-vegetarian diet, it is simply attachment of the tongue. Nobody dies without meat-eating. That's not a fact. When we were children, we were babies, we were depending on milk, either mother's breast milk or cow's milk. Therefore cow is also our mother. Just like we drink breast milk from my mother, similarly, we drink milk from mother cow.
Therefore meat-eating is prohibited. You cannot kill your mother. That is a great sin. You cannot. But people have become so sinful that they have no consideration that, "I am going to kill my mother. I am so ungrateful that the mother who supplied her blood to feed me, to keep me living, now I am grown-up, I am going to kill my mother." This is my advancement of education, that "I have learned how to kill my mother."
Therefore, in every religion the killing is prohibited or very much restricted. So in your Christian religion, the first item is, "Thou shall not kill." But everyone is violating this first commandment. Then where is your claim to become a Christian? If you violate the injunction given by Lord Jesus Christ, then where . . . how you become a Christian? That is our question. Either Christian or this or that, killing is most sinful. This should be avoided.
Therefore in the beginning, to increase attachment for Kṛṣṇa . . . because my business is to increase my spontaneous attachment for God. That is the business of human life. This is a chance. Because in the human form of life you can do that. And as soon as you increase your attachment for Kṛṣṇa, then your life is successful.
Successful means that you haven't got to accept any more this material body. You will get a spiritual body and go to Kṛṣṇa, or go to home, go to back to Godhead. So if you increase your attachment for Kṛṣṇa, the benefit is that you make a solution for all the problems of life. It is scientific. Mayy āsakta manāḥ pārtha.