I don't know if you thought of this yet, and this may not be your intention, but people outside your faith group (and possible some within it) may see you as being exclusive, and not open to doing business with folks outside your faith. You can still help out your fellow Christians, with out appearing as though Christians are the only ones you will do work for. Unless that is the goal and if so I believe you should reconsider.
This is no slam against religion, but in our 30 plus years of being in business, we have found that churches tend to want things donated. (which I can understand) Knowing that, I would think setting yourself up to target only one specific group would be detrimental to your business, especially a group that expects deals, discounts and donations.
Look at it this way: The more people you target, the more jobs available. In addition to more work being available to you, if you do honest good work, which I'm sure you do, the more successful your business will be. The more successful you are, the more you can help your local churches... or more importantly your fellow man.