Is the TV at church HDMI?
If so...
Step 1: Get a thunderbolt to HDMI adaptor.
Step 2: Connect an HDMI cable from the adaptor to an HDMI port on your TV.
Step 3: Press input or source on your TV remote to switch to the HDMI input.
Step 4: You should now see the desktop background on your TV and can drag applications over to it. If you want your MacBook display and TV to show the exact same thing (much better for TV and movie watching), set your Mac for
"mirror mode."
Step 5: To get audio going through the TV speakers, click System Preferences and then Sound. In the "Output" list in the middle, look for "HDMI" or the name of your TV and click it.