The real question, is how large of an event are we talking about? 40 to 50? 100? 300? Over 500?
If it's 40 to 50, all this person needs for speech and some bluetooth music is an affordable speaker that comes with a wireless microphone. It will get the job done. Won't be perfect, and might have a mic drop signal here or there, but these units usually work pretty good in rural areas.
My work uses a cheap Pyle Speaker on wheels that came with two wireless microphones in the warehouse when the manager is talking to 40 to 75 employees at short shift meetings. It doesn't sound great, and they can't walk far from the speaker with the mic without it losing signal, BUT it works. He has to crank the volume up near max probably because it doesn't have a lot of power probably only like 50 watts but it's just enough that everyone can hear when they are quiet and listening.
I would recommend this American Audio for a cheap option that is capable of handling a church speaking event in a field for under 100 guests. If this is a bigger event, then I would recommend a full set up like I recommended earlier.
Create the party where ever you are! There are a variety of ways to play music from the APX12 GO BT. • 12" Woofer with 1.5" Voice Coil. The APX12 GO BT features wheels and a retractable handle making it easy to transport to any indoor or outdoor event.
www.ebay.com