What is the worst sin one can commit?

In some passages, Srila Prabhupada mentions that cow killing is the worst sin one can commit, but in others, he mentions that illicit sex is the worst. Which one is the vilest?

Aug 07, 2025

In some passages, Srila Prabhupada mentions that cow killing is the worst sin one can commit, but in others, he mentions that illicit sex is the worst. This may sound like a contradiction at first, but it just means that both are very bad. In some passages of the scriptures is mentioned that Nārada Muni is the greatest devotee, and in others that Lord Śiva is the greatest devotee; it just means that both are pure devotees. Similarly, both cow killing and illicit sex are very dangerous.

It is easy to understand why cow killing is so terrible. The cow is not only the most evolved animal before human beings, but it is also the most useful. Cows give not only milk, but also dung, which is the best fertilizer. Bulls give physical labor, and thus cows and bulls give us everything that is necessary for successful organic agriculture and feeding people. Without cows and bulls, life becomes miserable. People were living without cows in parts of Europe during the Middle Ages — using human excrement and slave labor — but this is not a level of existence that most of us would appreciate.

It's easy to understand how killing cows and other innocent animals is so terrible, due to the violence and suffering involved, but what about illicit sex? Sex, illicit or not, involves only two persons, and as long as it is consensual, it doesn't involve violence. What's the problem with it?

First of all, we need to understand the definition of illicit sex used by Srila Prabhupada. There is legal sex, which is sex inside marriage with the purpose of begetting children, and there is illicit sex, which is promiscuous sex outside of marriage. The idea given in the Vedas is that sex is a very serious thing since it determines which souls are going to take part in the next generation. We may be completely non-violent, but if due to our lack of responsibility, we beget demoniac children, they may cause much more harm than we could ever do. Because of a mistake by Diti and Kaśyapa Muni, two great demons came, who terrorized the whole universe for thousands of years, including the killing of cows and brāhmanas.

According to the Vedas, children are not just tabulae rasas; they bring all the impressions, desires, and traces of personality from their past lives. A pious soul can be easily trained as a brāhmana, saintly king, pious businessman, or pure Vaishnava, who can greatly benefit the world. On the other hand, a demoniac soul will cause a lot of suffering to others.

We don't create a new soul during the sexual act, but we create a new body according to the state of consciousness of the father and mother. The type of body created will, in turn, determine what kind of soul will take shelter in it. If our consciousness is pure, the body of a pure devotee will be created, and a pure soul will come, but if our consciousness is polluted by lust, violence, and so on, the body of a demon will be created, and the result will not be so good.

When one has sex with someone else's wife, or with some random woman or man from a bar, he or she may end up bearing the responsibility of bringing one of such dangerous souls to earth. Naturally, nowadays people avoid the risk of pregnancy with contraceptives, but they bring other problems. Not only are contraceptives never 100% effective, but they also bring negative karmic consequences for breaking nature's laws, just like abortion and other acts.

Sex is accepted as an important necessity in the Vedas, but on the other hand, the scriptures alert us to the necessity of doing it in a responsible way, by constituting a family and begetting good children. This is not only a great merit for us, but also the best for the whole world.

In the Bhagavad-Gita, Krsna explains that enlightened souls who practice devotional service in previous lives have the opportunity to take birth in pious families, where they will be well treated and will have conditions of continuing their spiritual path. Souls who are even more evolved take birth in families of serious devotees, where they are trained from the beginning in the service of Krsna. Nowadays, such families are becoming increasingly rare, and that's the source of most of the problems we have.

Much is spoken about overpopulation, but overpopulation is only a problem when demonic souls are born. If the world were overpopulated by pure devotees, it would become Vaikuṇṭha. The problem is thus not about avoiding overpopulation, but bringing the right type of souls to our planet.

It's difficult to speak about building a Krsna Conscious society, or any kind of progressive society, without accepting our responsibility connected to it.

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