Yeah great idea. Finish off with a chorus song - they always go down well.

1) If you're Jewish and you know it, clap your hands (clap! clap!)
2) If you're Orthodox Catholic and you know it (clap! clap!)
and so on

Pehaps an encore of I'm a believer!

(Agnostics can be exempted - if they can prove they are not now, nor ever have been - a member of the Monkees Fan Club.)