Asalamoalikum ! I want to know more about Why Ahmadiya are considered Non-Muslims? Can someone please provide me with extensive detail? JazakAllah:)
Because they believe in and follow Mirza Ghulam Ahmad who claimed to be a prophet and claimed to have received revelations. This is contrary to core Islamic belief of the end of prophethood with Muhammad ﷺ. They also deviate in other beliefs which are considered necessities of religion, e.g. they believe that Jihad has been abrogated.