I'm not sure why MagikCards is leading you to believe that Clerics deal damage. They are, understandably, the worst damage dealing class in the game, by far. Their only form of offence is a skill called Smite that will realistically deal 70 true damage to your opponent on a 7 second cooldown. It is very possible that you can 1v1 any class in the game as long as your kiting skills are superb, but it will take awhile to do it, and it won't be pretty. 1v2ing is out of the question since Clerics don't have a mana replenishing skill. Once you're out of mana you'll just have to kite until you can smite or heal again.
He did get something right though, a Cleric is the superior healer, hands down. He has many target based and party-wide heals alike. If you don't mind having multiple key binds for multiple players, and you plan on having big party raids then Cleric is the right class for you. You will be able to keep your team alive longer with your presence, and they'll love you for it. You will seldom kill any players however, and from experience the class got boring for me after awhile.
Long story short, if your goal is to always be with a group of people and keep them alive, Cleric is the right choice. Have fun.