Comment Get an AP with "Guest Network" capability (Score 1) 332
Get a new wireless access point. Many new models include what you're looking for. They appear as if they are multiple Access Points. Make two networks:
ChurchBusiness: WPA2 security, user accounts or strong password; full access to internal network
ChurchGuest: Security either as WPA2 password, or no wireless encryption and web redirect to authentication page; has only access to Internet, no church net access.
Many new routers under $200 have the ability to do the above. The Apple Airport Extreme can do the above, as can various Netgear or Linksys. Pick one up at a local retailer, give it a try.