What is Major Shirk (polytheism)?
It is to devote any forms of worship to one other than Allah.
Evidence from the Noble Qur'an
{Verily Allaah forgives not that partners should be set up with Him in worship, but He forgives except that to whom He pleases}, {Soorah an-Nisaa., verse 48]
Evidence from the authentic Sunnah
((The greatest sins are polytheism etc.)), [Transmitted by Muslim]