Slaughtering a sacrifice to other than Allah (Exalted be He) is major Shirk (major form of associating others in worship with Allah), as He (Exalted be He) commands saying (what means),
Say (O Muhammad صلى الله عليه وسلم): "Verily, my Salât (prayer), my sacrifice, my living, and my dying are for Allâh, the Lord of the ‘Alamîn (mankind, jinn and all that exists).
"He has no partner. And of this I have been commanded, and I am the first of the Muslims."
Moreover, the Prophet (peace be upon him) cursed anyone who slaughters a sacrifice to other than Allah (Exalted be He). Visiting, consulting or believing such charlatans, soothsayers or anyone who practices acts of Shirk are strictly forbidden.May Allah grant us success. May peace and blessings of Allah be upon our Prophet Muhammad, his family and Companions!