Rubuta ci gaba don wannan sakin layi - Doria ya yi karatun falsafa da ilimin tauhidi a Spain wanda aka inganta shi zuwa Cardinalate a kan Sarki Felipe II na Spain. Da zarar sarki Philip II ya mutu, an nada shi kardinal deacon, yana da shekaru 31, a cikin taron na Yuni 9, 1604. An ba Doria izinin karɓar umarni mai tsarki a waje da ranakun Ember, 9 ga Disamba, 1604. Ya halarci duka biyu na Maris-Afrilu 1605 papal conclave
, wanda ya zaɓi Paparoma Leo XI, kuma a cikin watan Mayu 1605 papal conclave, wanda ya zaɓi Paparoma Paul V.