So, the question of the day was about how to catalog a church's library.
This article has some great suggestions especially in regards to collection management decision making.
In addition to determining which audience level, type of media, and subject headings schema to use (Sears, LCSH, etc.), I would add to also figure out how you want to provide access to the catalog and what you want to use it for. Do you want a system where you can also circulate items? Can you host it on your server or does it need to be hosted elsewhere?
Hosted elsewhere solutions
LibraryThing.org: many small libraries have used librarything to catalog their items; Community contributed records but no checkin/checkout functionality
Hosted on your server (software)
Opensource. Features include membership creation, assigning/printing barcodes, an online user-searchable cataloge, run circulation tasks, etc.
Biblios.net, http://biblios.net/ Biblios.net has a webbased cataloging client and allows for sharing of records, although you'd need a database to then put your work back into.
Lots of choices at this website.