I once built a political speaker "cue" system which consisted of a little plastic transmitter box at the console with a 9-volt battery and a pair of momentary/toggle switches that would send a positive or negative polarity signal up a mic wire in a snake. The receiver box at the podium had a two-color LED that would change colors with polarity. So I could send a green light for the person to start speaking, blink a red light when they had 30 seconds left on the clock, and a solid red when their 3 minutes (or whatever) was up. Worked great for the political/public forums I was doing at the time.
It would be pretty simple to make this a two-way system with transmit buttons and receiver LED's on both ends so you could signal the pastor, or the pastor could signal you. Pin 2 on the XLR could be the transmit channel to the podium and pin 3 could be the receive channel back to the console position. You could plug this into any hard-wired snake return or home-run a mic cable. You could also use two LEDs of whatever color you like and add diodes for the positive or negative polarity visuals.
I've got the schematic laying around somewhere, but it's a very simple build that should cost less than $20 even if you have to buy new parts at radio shack.