What do the pantheists mean by the unity of existence, and what is the refutation of them?

The belief in incarnation (hulul), union (ittihad), and the oneness of existence (wahdat al-wujud) is considered a refutation of Islamic law (Sharia) and a contradiction of reason. Islamic law has clearly articulated the distinction between the Creator and the created, stating that Allah is the Lord of the worlds, the Creator of all things, and the Irresistible above His servants. Adherents of this belief claim there is no worshiper and no worshipped, with one of their proponents even saying: "The Lord is a servant, and the servant is a Lord; oh, would that I knew who is held accountable!" They consider Pharaoh not to be an unbeliever because he supposedly recognized the truth when he declared: "I am your most exalted lord" and "I do not know for you any god other than me." Yet, Allah has revealed Pharaoh's fate and punishment: drowning in this world and entering hellfire in the Hereafter.