Say I’ve got an idea for a web-based business which would employ holy men from a wide range of religions so a visitor could post a request for a prayer to be intoned in the faith of one’s choosing. Someone could could click on the site to ask for a Buddhist monk to pray for a loved one’s successful recovery from surgery or for a rabbi’s prayer that the home team wins the next ball game.
Are there any methods could I employ to protect myself from competitors replicating my idea?
Ideas are always replicable. Only the individual expression of those ideas can be protected.
This isn’t your actual idea. Please tell me this is just a hypothetical and isn’t your actual idea.
The methods of protection one would traditionally employ is to corner the market by offering the best service at the best price, and promoting your sevice aggressively.
To be honest, it’s pretty much the same with patentable ideas too; you protect them by implementing them, seeling lots of units and making a fat profit; without this, you cannot employ expensive lawyers to ensure that your patent rights are upheld.
I seriously doubt that you would get any legitimate clergy to do this, and I would seriously doubt the validity and ethics of any clergy willing to do this.
As for “protecting” the idea, unless you can patent it, no. That is the purpose of patents, protecting novel ideas and applications.
The most you could do is to reserve the domain, trademark the distinct business terms and such.
But I seriously doubt that this is patentable.
No, that is not my idea. (Anymore.) 
I was really curious about eBay and whether they could have done anything to have protected the idea of using the internet as a venue for conducting virtual auctions. Since I didn’t want to get caught up with the particularities of a specific example, I made up my own “business”.
You could log onto the site to ask Ashlee Simpson for more information on striking deals with Satan.
Some things that are not patentable can be protected as trade secrets, which requires steps to protect the stuff from outsiders. (Most of the stuff done inside a big company falls under this class) That won’t work for your idea, since it is obviously open to the public.
These days, don’t underestimate what can be patented. If you pretend it is a process, implemented on a computer device, you can get away with a lot. If you are serious about this, I’d advice spending the money to talk to a patent attorney for some real advice.
If you are Hindu, you can already do it.
http://www.eprarthana.com/poojas/index.asp
Note that this isn’t really unusual. Most Hindu temples in India come complete with a price list for various rituals- from marriages to car blessings. In the end, it’s really not that different than the old tithe’n’basket shakedown that Christian churches use.
There are also countless religious message boards, from all religions, that include “prayer request” sections.
It’s possible that the founders of eBay could have invented some patentable algorithms in the creation of their business. For example, their proxy bidding protocol might have been patentable (I don’t know if it was really a new idea). I doubt they could have patented the idea of on-line auctions, though - patents have to be more specific than this. Even if eBay had patents, it would probably be possible to implement on-line auctions to compete with eBay unless they patented every conceivable way of doing it.
eBay’s ability to succeed against Yahoo and other competitors in the on-line auction business came largely from the fact that eBay had a head start in creating a marketplace. The competitors had to convince sellers to go with them despite the fact that the buyers were all over at eBay, and the buyers weren’t going to spend much time shopping at the competition if the sellers weren’t there. This sort of advantage is very hard to overcome, as it requires a large number of people to change their minds all at the same time.