Your question is actually very general. The Right AnswerTM involves the number and location in the building of expected users (lots in a sanctuary or classroom, few in the office area, etc), the logical separation between different types of users (public Internet users versus office users who might be accessing LAN resources), the physical layout of the structure (for AP placement and cabling concerns), and knowing how to perform wireless site surveys with whatever APs you select (depending on your budget and necessary features) and test client devices (because the antenna characteristics of a laptop are very different than an iPod Touch, etc).
It sounds like you're coming at this from a level of understanding that will cause you to have a very, very steep learning-curve. You may want to get a professional with experience in these kinds of deployments to come in and give you some pointers. If you're looking at supporting more than 20 - 30 active clients in a large open room then you probably need professional assistance. There's a pretty vibrant "church IT community" out on the 'net, and you may be able to enlist some support there.
I'd be wary of using wireless "repeaters" if you want any significant number of users active at any given time. Wired back-haul from multiple access points will give you the best aggregate bandwidth in the air. That means running cables, so you'll want to be certain you've tested your planned placement for APs to be sure they give you the coverage you need before you start running cables.