Ummm... my question was what religion do Sikhs practice?
Sikhs practice Sikhism ~ that's why they are Sikhs.
Sikhs practice the religion called Sikhism. In general they follow the teachings of Guru Nanak and are neither Muslim nor Hindu though the religion reflects a background from having been born in the struggle between Muslims and Hindus.
Sikhism.....the religion was started as an offshoot oh Hinduism in response to the barbarous Islamic genocide in India in the 15th and 16th centuries. The eldest son and daughter in each Hindu family was converted to sikhism voluntarily so that they would serve as a warrior community against Islam. Over time, Sikhs became a separate religion. IMO, there is nobody on earth who hates muslims as much as Sikhs do.
Ah, so. According to Muslims, they're heretics. They combined some of the tenets of Islam with the Hindu religion. (It's that three million gods thing.) They carry a Kirpan, a sacred dagger, as a symbol of their dedication to the tenets of their religion, which seems like a good idea of you're going to PO some of the stricter sects of Muslims. They also wear turbans.