"Of course, I don't know what your church requires out of a p. a. - some services get pretty involved, with a full scale band and all."
The church I go to is like that. We've got a sound system that would make almost every other church (and every other church around here) jealous It's REALLY nice. And it gets used a lot. Same with the lighting.
For the original poster, 3 speakers total? With one a bass channel? That's seriously nowhere near adequate to fill all but a tiny room.