Typically, houses of worship are buildings without any kind of acoustic treatment on their interior surfaces. Most of them were built decades or centuries ago and at that time acoustics was not a major issue. Walls, ceilings and floors reflect the sound easily, creating reverberation and so poor intelligibility.
If we want voice messages to reach the audience in a very clear and intelligible way, we will need to digitally process the audio signal in order to reduce low frequencies that mask mid and high ones, where human voice intelligible information is mainly found. Additionally we will have to use very directive loudspeakers that minimize acoustic reflections on surfaces (walls, ceiling, floor, furniture).
Choosing the right equipment, the one that assures audio quality and intelligibility, will be a must.