Yes, but you'll need to remember that the mic will be much further away from the minister's mouth, so it won't pick up as much as the one he's using now. You've probably noticed how much the sound level drops off if he moves away from the mic.
There's a limit to how much you can turn mics up before you start to suffer from 'feedback' or 'howlround' and you'll probably find that it's impossible to go far enough to make it work.
Another thing you'll notice is that the fixed mic is probably quite directional and the lavalier won't be. That just makes the feedback problem worse, as the fixed mic will (should) be pointing away from the speakers and you've no control over the lavalier.
I use a headband mic with a radio pack to solve both problems. The mic is a constant distance from my mouth, so the volume stays constant and it has a directional pickup, so it doesn't feed back as soon. Good luck.