It’s possible to play a priest without Divine Favor simply choose the Professional skill Counseling/Priest and assemble an appropriate set of skills. But such a priest has no ability to use Clerical Magic. Note also that you don’t have to be an ordained priest in any religion to have Divine Favor or to use Clerical Magic.
Skills available to a character with Divine Favor include the mundane and the supernatural. The supernatural are cast strictly through the power of the God or gods served by the cleric. If the cleric’s behavior is inconsistent with the God’s desires, this ability is withdrawn, at least temporarily.
Supernatural skills in the following list are detailed any other skill is mundane and uses the description in the Skill list. This list assumes a benign deity who grants free will and supernatural aid to its followers in times of crisis. Other skills may be appropriate for other types of clerics plant magic for Druids, for example, and more spirit magic for shamans. Evil clerics have a different skill list your characters should pray they never meet them. . . .
Aid Task: by touching someone who is trying to accomplish a task that is in the deity’s interest, you can grant a +1 to their skill.
Banish Spirits: you can force spirits and demons from another plane to return to their proper plane.
Bless: you can grant a +1 (or more, if the GM is willing) defensive bonus to someone, which lasts until the next combat ends.
Detect Lies: your ability at this is enhanced.
Exorcism: you can force a spirit or demon which has invaded a body or dwelling to leave.
Healing: you can channel healing from the deity you serve.
Remove Fatigue: you can restore endurance to the weary.
Repel Undead: you can ward off zombies, vampires, ghosts, etc., from your presence.
True Sight: you can see through illusions.
Ward: you can protect a person or all within a room-sized area from supernatural evil, either spells, spirits, undead, demons, etc.