Let there be Light
Make sure you take measurements of ambient light during the time of day that services take place, and arrange a demo with a screen and the projector you intend to supply. You will set the proper expectations of brightness and clarity for the decision makers, and assure the worship experience is optimized.
Remember that lumens have to be divided by the area of the screens to get a real idea of how bright the image will be. Factor in times during the service that the screens are in use. If there are gaps in between the visual content, make sure you allow for warm up and cool down times on the bulbs in your programming set up, or for AV muting in between.
Factor in the interference that may be caused by the screens raising and lowering, and what they may block when they do. I have seen churches with ornate wooden crosses, backlit with LEDs where a screen comes down five minutes into the service, blocking it from view, and it stays down until after the service has ended.
Many of these issues might entail a little more cost upfront. But if you position these installation recommendations correctly to the decision makers who write the checks, letting them know that you are thinking like a parishioner and not a salesman, they usually find a way to raise the extra money and are blessed with a system that draws their congregation closer together, without sitting through a commercial for your equipment manufacturer.
Related: A Guide to House of Worship Lighting Design
