DnD Paladins do this. They Smite Evil, channeling the power of Good to smash Evil's face in.
They channel the power of their god to do that - not the belief of a billion or three people.
Nor do they bypass all damage reduction.
In Exalted, Solars do this. They have access to Holy effects, which deal aggravated damage to Creatures of Darkness and can pierce some of their defenses.
Again, works differently.
They aren't channeling the belief of the Christian world to do it.
In (new) World of Darkness, blessed objects are one of the few weapons effective against ghosts. Blessed objects and ghosts are the only supernatural elements statted out in the core book.
Again, blessed objects in the nWoD do not channel the belief of a billion or three people. Nor do they do agg against all things.
Knights of the Cross are just about as generic as you can get, actually. They're just guys with holy swords, one of the oldest tropes in the book from which ideas like the paladin first gestated. http://tvtropes.org/pmwiki/pmwiki.php/Main/HolyHandGrenade Here's an article on people who use that kind of mechanic from various forms of media.
(please note: since this forum has specific rules against religion debates, I'm pointing out that the text below refers ONLY to the DV. I am not endorsing (or slamming) any real world religious beliefs - I am only referring to religion as portrayed in the books.)
Holy knights are generic.
Three Knights who use Swords forged with the iron from the nail of the Cross aren't. Now if they were an order - say 50 or 60 carrying relics - then I could see them as generic holy knights. But they aren't. They are hand picked by Archangels (who directly serve the will of God) and given something that has touched the Blood of the Lamb.
Perhaps more importantly, unlike Paladins, Exalted, etc - they are not given powers directly. They merely use a Sword that is a direct link to all who believe in the Crucifixion. That Sword, whose iron is soaked in the Blood of the Lamb, has the power, not the person using it. And if the person using it isn't of pure heart and purpose then it just doesn't work.
Micheal doesn't have the power that his Sword has - he merely uses the Sword. If unarmed he still has Faith but not all creatures are equal.
Show me anything that predates Storm Front that has something like that - because I haven't seen it.
Richard