Existence of God
In his book "The Miracle of Theism: Arguments for and against the Existence of God", the Australian philosopher J. L. Mackie noted that whilst in the past a miracle performed by Jesus had served as proof to Christians that he was the 'one true God', and that a miracle performed by another religion's deity had served as a (contradictory) proof to its own adherents, the universalist approach resulted in any such miracle being accepted as a validation of all religions, a situation that he characterised as "Miracle-workers of the world, unite!"