Returning some portion of the experience normally lost to characters through death
Some group leaders or players insist that a cleric should not engage in combat at any time, but just cast heal spells as needed Cabal Alz, and when not casting, sit and regain their energy.
To play a cleric, one must accept that your role may not be at the front of the combat, but rather to the rear, ready to act at a moments notice.
Not that there is not excitement in the life of a cleric. Battles are won and lost by the actions of clerics, and one needs to keep a cool head to act in the best interests of your comrades, sometimes letting others die to keep the tank alive.
Clerics also gain a powerful line of resurrection spells, enabling them to raise the bodies of their fallen comrades, returning some portion of the experience normally lost to characters through death.
Clerics are a plate armor wearing class, and as such, can take a bigger beating than other casting classes, and healing spells do get the enemies attention.
Monsters are often known to break combat with the main tank and rush the cleric, if their healing spells draw to much attention to themselves. While limited to blunt weapons, clerics can wade in and fight when called to do so.