Who is Grand Inquisitor John Domenico Mustafa from The Rise of Endymion and what is their importance?

Grand Inquisitor John Domenico Mustafa is in charge of the Inquisition. His devotion to the Church is based upon the power it affords him more than anything else, but even Mustafa is deceived by the Church's real motives. When he learns about the Church's relationship with the Core he is appalled..... a true revelation when you consider Mustafa's own dishonest and immoral traits.