Re: Making the most (or least) of a bad room.
Get rid of the Monacors, they are not helping. If you can, rent a larger pair of loudspeakers with a narrow dispersion pattern and a larger horn(which will have a lower useable frequency range than the little horn in the 15" Thomann loudspeaker). Get them up higher on larger stands if possible. Flying them high and aiming them down at the parishioners is always a good thing. The Thomann cabinets are just not even close to the right cabinet design to use in this space, they are spraying a lot of energy out far and wide and bouncing off the walls, causing a lot of the problem.
Also, is this system just for spoken word, or is there a choir or band running through the system as well? Microphone choice may help some.
The other issue is a lack of acoustical treatment in the room to reduce the amount of reverberant energy v. direct energy. This sounds like a desperately lousy room for that. Some kind of absorption panels are needed, probably some behind the speakers in the area where the pastor/choir/band are positioned, and then some along the walls in front of the loudspeakers(if they stay where they are) and up along the ceiling near the speakers(depending on the how the ceiling design meets the walls. Catch and absorb some of that early more intense energy before it reflects back into the path of the direct sound from the loudspeakers, and hopefully tame some of the reverberation in the room.
Many here will recommend hiring a consultant to evaluate the room and specify recommendations to help with acoustical treatment and sound design. I do as well, but you mention that the congregation probably won't spend money on improvements, so doing something themselves or yourself becomes the only option. There are DIY possibilities for acoustic panels as well as commercial. Be careful if you make something, use fire rated materials.
Renting other loudspeakers to experiment and show the congregation(or the church leaders) some significant improvement may motivate them to make the move to upgrade.
Good luck,
John
