For me, the scariest worship service is one where the congregation waits on God alone to speak and act. The minutes pass, and you can’t fill in your uneasiness by reading the bulletin, because there isn’t one. You can’t wait for the next part of the program to begin, because there is no program. Nothing at all happens unless God speaks, and you can’t break the tension by sharing your own pious or clever thoughts. It won’t work, because the leaders are mature enough to tell if it was God who spoke through you, or man.