There comes a point when the preacher says, "if anyone is outside of Christ..." Zip, ziiiiiip, shuffle, squirm and we're done listening.
Do you not realize that at this very moment someone may be raging a great spiritual battle inside themselves? Not to mention that it is just plain rude to the speaker to stop listening before he is done speaking.
"But, I'm already a Christian. I know what he's going to say,"
Sometimes important things need to be said over and over again. Sometimes we need to be reminded.
But by closing our ears and not listening we act like insolent teenagers that know it all. God would not be pleased with that behavior.
Please let's be concerned and caring of other listeners, let's be respectful and attentive to the speaker, but mostly let's be reverent to The Lord, God.