Distortion comes from many sources. It may be a cheap mic overloading, it may be the input of a cheap amp overloading, it may the the output stage of an underpowered amp overloading (that, and only that, will be "clipping") it may be inadequate speakers (or speaker cabinets). To avoid most of these things - turn it down.

Mics can be picky. So long as there is enough headroom to TURN IT DOWN a pair of the "old standard" SM58s - a "cardioid" microphone angled in towards the middle of the lectern plus a soundman with hands and ears should be able to create a reasonable simulacrum of the human voice. The SM58 itself is almost impossible to overload.

Churches have lots of natural echo. This is what gives music in churches a wonderful sound (sometimes).

To reduce echo, turn it down, point the speakers towards the middle of the rear of the room, and put curtains on the back wall.

Speakers are vital. No matter what you put into a system you will only get out what you can get out. Peaveys are the Dr Dre of loudspeakers - (ask a young person who listens to MobO (Music of Black Origin) about Dr Dre. Big thud at about 60 Hz, (low-ish, out of range for human voice) and scratch at about 8,000 Hz (will make "S" sounds splashy). Don't go there for spoken word.

15 inch drive cone drive units will sound chesty on spoken word. Many compression drivers will sound scratchy on spoken word.

I'd suggest something not too loud, 12" main drivers, and maybe even hifi tweeters.

I normally amplify rock and metal. I like it loud and have been heard to say "If it's too loud you're too old" - I'm 62 - but loud and proud is not what you need here.