Spiritual Regulative Principles
It is said that by chanting we get a higher taste so that we lose interest in material things and thus we automatically start following the regulative principles. If this is the case, then what is the use of following the four regulative principles [no meat-eating, illicit sex, intoxication, or gambling] till we don't get a taste in chanting?
When we get a higher taste by chanting, it becomes natural and easy to follow the regulative principles. We become more attached to Krishna and detached from matter. But until such time, we should follow the rules, even though they may be difficult, because that way we show the Lord we are trying to give up sense enjoyment separate from Him. If we don't follow the rules, then chanting becomes even harder—like trying to cook while simultaneously pouring water on our cooking flame.
Furthermore, for success in chanting, we have to avoid the ten offenses to chanting. One offense is to maintain material attachments, which would surely include not following the regulative principles.
There's a difference between chanting Hare Krishna and following the process of Krishna consciousness. Anyone can chant anywhere and anytime and get spiritual benefit. At the same time, any mantra is more potent when received from a teacher and chanted as part of a self-purification process.
Any formal training requires discipline. The same way that scientific experiments and manufacturing processes often require controlled environments to achieve accurate results, when we avoid things that reinforce our material illusion, chanting the Hare Krishna mantra can more profoundly enhance our natural, spiritual consciousness.
Initiated devotees within the Krishna consciousness movement vow to chant a minimum quota of the Hare Krishna mantra each day on beads. They also take vows to avoid 1) intoxication, 2) illicit sex, 3) meat-eating, and 4) gambling. These are commonly known as the "four regulative principles."
Meat eating, illicit sex, intoxication, and gambling increase attachment to the body and the material world, so avoiding them helps our spiritual life.
Animals are also souls and to kill them unnecessarily is a great offense. By God's grace we can live perfectly well, and actually better, eating a vegetarian diet. If we're killing our brothers and sisters—the animals—and eating them, how can our Father be pleased?
Gambling is based on untruthfulness; trying to get something for nothing. Some examples are lotteries, slot machines, black jack, etc. One should labor honestly and accept what comes as God's mercy. Subtle examples of gambling include time-wasting activities like frivolous games and spectator sports. While these aren't considered grossly sinful, they don't help anyone's spiritual life, either.
Intoxication impedes clear thinking and makes it harder to remember God and do His will. Intoxicants are themselves material compounds; becoming attached to them binds us more to this material world.
Sex is meant for procreation of offspring, who are, in the ultimate issue, children of God, and thus should be educated to understand the human form of life is meant for developing our relationship with Him. Sex for that purpose is religious. Otherwise sex attaches us very deeply to our material bodies, the bodies of others, and this whole material world. Sex outside of marriage or outside of the purpose of having a child is considered illicit.
More on this topic: Four Regulative Principles