Muhammad ibn Abd al-Wahhab
Muhammad ibn Abd al-Wahhab did not accept that view. He argued that the criterion for one's standing as either a Muslim or an unbeliever was correct worship as an expression of belief in one God ... any act or statement that indicates devotion to a being other than God is to associate another creature with God's power, and that is tantamount to idolatry ("shirk"). Muhammad ibn Abd al-Wahhab included in the category of such acts popular religious practices that made holy men into intercessors with God. That was the core of the controversy between him and his adversaries, including his own brother.