You’ve gone out of your way to support a friend or family member at a recognition ceremony. “Congratulations man! What an achievement! Hold on a sec… just received some new e-mail spam.” Turn the phone off and avoid the insult of interacting with your smartphone while someone is being honored.
Ditto for religious services. You have made the choice to attend and participate in your religion – a time to reconnect and reflect. Neither of these things have anything to do with your phone’s signal connection or whether you can see your reflection on the screen.