The fire alarm

Church packed. Songs sung. Prayers said. Notices read.

There was a calm and silent atmosphere as people sat in quite reflection. But then the peace was shattered by the insistent shrill wailing of a fire siren. As the deafening racket continued, an announcement came over the PA system:

"There is a dangerous fire in the building. You must calmly get up out of your seats now, and leave the building."

The siren continued to wail for a time, but eventually it stopped, and the worshippers sat in their rows looking nervously around at each other. Eventually, they began to talk:

"Wasn't the sound of the siren interesting!" said one woman.
"Yes", replied another, "Once you got used to it, it was really quite lovely."
"I though the announcement was very clear and helpful", said a man.
"I've made some great notes that have got all the main points down" said another.
"I didn't find it that interesting - no funny stories or jokes at all" said a sullen teenager.

The excited buzz of conversation continued as the smoke slowly filled the room…

Q: How do we know when people have truly heard the fire alarm?
A: When the building is empty.

Q: How do we know when people have truly heard a sermon?
A: suggestions below please...

Based on an illustration heard from Mike Cain at the Planting for Christ Conference last week.