The discipline of silence is arguably one of the most neglected disciplines among Protestants. But even those who are aware of it often fail to practise silence because they find it uncomfortable and get restless very quickly. This morning as I was reading a sermon by Bonhoeffer, I came across Bonhoeffer’s thoughts on why many of us struggle to observe silence. The following is extracted from a sermon he preached on July 15, 1928.
There are two simple reasons. First, we are afraid of silence. We are so accustomed to commotion and noise that we are uncomfortable amid silence; we flee silence; we race from activity to activity to avoid having to be alone with ourselves for even a moment, to avoid having to look at ourselves in the mirror. We are bored with ourselves, and often the most desperate, wasted hours are those we are forced to spend by ourselves. Not only are we afraid of ourselves, of discovering and unmasking ourselves, but even more we are afraid of God, that he might disturb our aloneness and discover and unmask us, that God might draws us into partnership and do with us whatever he wants. Because we fear such unnerving lonely encounters with God, we avoid them, avoid even the thought of God lest he suddenly gets too close to us. Suddenly having to look into God’s eyes, having to be accountable before him, is too dreadful a notion; our perpetual smile might fade, things might get completely serious in a way to which we are not at all accustomed. This anxiety characterizes our entire age. We live in perpetual fear of suddenly being seized and called to task by the infinite and would rather socialize or go to the movies or theatre until we are finally carried to our grave, anything rather than having to bear a single minute before God. Let us examine ourselves and see to whom some of this does not apply. This is one reason. The other is that we are too lethargic and lazy in our religious lives. Maybe we once made a good start, but ah, how quickly it lapsed. We protest that we are just not in the mood, that religion is a matter of mood and one must wait until that mood comes upon us; and then we wait, and often wait for years, maybe even to the very end of our lives until we are once again in the mood to be religious. But this position conceals a great deception. Fine, let religion be a matter of mood; but God is not a matter of mood; God is there even if we are not in the mood to come together with him. Does this thought not worry us at all? Those who depend on their moods become impoverished. A painter who paints only when in the mood will not get very far. In religion, as in art and science, times of high tension alternate with times of sober work and practice. Contact with God must be practiced; otherwise [we] can never find the right tone, the right word, the right language when God surprises us. We must learn the language of God, laboriously learn that language; we must work so that we, too, are able to speak with God. Prayer must also be practiced through serious work. Confusing religion with emotional daydreaming is a grievous, fateful error. Religion takes work, perhaps the hardest and certainly the most sacred work a person can undertake. It’s pathetic to make do with the assertion, “I’m just not religiously inclined”—when there is a God who wants us. That’s just an excuse. No doubt, it’s more difficult for some than for others. But we can be sure that no one has attained it without serious effort. And this is why silence before God, too, requires work and practice. Such silence requires the daily courage to expose oneself to God’s word and allow oneself to be judged by it; it requires the spontaneity to rejoice in God’s love every day. 
 Dietrich Bonhoeffer, The Collected Sermons of Dietrich Bonhoeffer, ed. Victoria J. Barnett (Minneapolis, Minn.: Fortress Press, 2012), 36–38.