In A Feast for Crows, the High Septon refuses to annoint Tommen as the true king because there are many claimants for the throne and by throwing his weight in with Cersei, he may be selecting someone unfit to rule. This, of course, makes Cersei very angry, but she tells the Septon that if he will annoint Tommen and forgive the crown's debts that she will in return protect the faith and allow the Septon to reinstate the old order of warrior priests.
