Superstitions and meaningless Rituals: Sikhs are forbidden to believe in any superstitions or to under take ritualistic practises, which have no meaning.
Pilgrimages to holy places are discouraged as it does not in anyway enhances the person’s inner self.
Fasting as a penance does not bring the person near to God and is of no spiritual benefit. However, if one uses this for medical reasons, then Gurbani does not speak against it.
Bathing in rivers; gambling; circumcision; worship of graves, idols & pictures; compulsory wearing of the veil for women, etc are all forbidden.
Cutting Hair: Cutting hair is strictly forbidden in Sikhism for Khalsa Sikhs and strongly discouraged for non-Khalsa Sikh. This includes from your head down to your toes, no hair is to be plucked, cut, burnt or chemically/surgically removed. Kesh (hair) should not to be dyed by any method whatsoever.
Behaviour under influence of Maya
“Maya” – The accumulation of materials wealth has no spiritual meaning or benefits to Sikhs. Wealth, Gold, Portfolio, Stocks, Commodities, Properties will all be left here on Earth when you depart. Do not get attached to them. They are only a means to help the person for their short visit during this present ‘Joone’ or human life on Earth.
Slander, bragging, gossip, lying,"back-biting", etc are not permitted. One must not indulge in these practises as by these feeble acts, ones mind and body are ‘diluted’ or weakened. etc. are not permitted. The Sri Guru Granth Sahib tells the Sikh "Your mouth has not stopped slandering and gossiping about others. Your service is useless and fruitless.(1) (SGGS Page 1253) 
All types of intoxication is not allowed in the Sikh religion. Drinking alcohol, Drugs, Smoking tobacco are completely forbidden. The Gurus speak strongly against the consumption of all types of intoxicants.
In Sikhism, the husband and wife must be physically faithful to one another. People who allow lust to overcome them and violate this rule will not escape the circle of life and death.
Sacrifice of Creatures
Sati – widows throwing themselves in the funeral pyre of their husbands; lamb and calf slaughter to celebrate holy occasions; etc
Eating Kuttha Meat: Eating Kuttha meat is strictly forbidden for a Khalsa Sikh. Serving meat at langar is strictly prohibited and meat is strictly not allowed on to Gurdwara premises. Eating Kuttha meat for a non-Khalsa Sikh is strongly discouraged. A vegetarian diet has been deemed as consensually (consensus or Gurmatta is a Sikh tradition) acceptable to all, on religious occasions and gatherings. According to the Rehat Maryada, eating of Kuttha meat is a taboo and a serious transgression for a Sikh. It bans the consumption of halal and kosher meat and states that "Eating the meat of an animal slaughtered the Muslim way must be avoided;" [Reference: Sikh Rehat Maryada - Section Six] and this forms one of "four transgressions" that are regarded as a cardinal sins for the Khalsa Sikh. The Guru Granth Sahib discourages the consumption of all meat including fish - see SGGS on meat
Non-Family Oriented Living
A Sikh is not allowed to live a recluse, beggar, yogi, monk, Nun, celibacy, etc. Gurbani, the word of the Guru, tells the Sikhs to live the life of a Householder. To raise a family; to earn honestly; to help the community; to educate the children; to remember God at all times.
No priestly Class
Sikhs do not have to depend on a priest or clergy for any of the functions that need to be performed in their religious duties. The religious acts have been made very simple so that most Sikhs can carry these out themselves in their daily lives.
|These articles deal with Sikh Beliefs|