Some churches specialize in generating emotion. The platform people are experts at moving worshipers to laughter or tears. Attenders gradually learn to evaluate the service in terms of the emotion they feel.

In time, however, the law of diminishing returns sets in. Prayers are offered in highly emotive style and bathed in background music. Stories have to get more dramatic, songs more sentimental, preaching more histrionic, to keep people having intense emotional experiences.

Such worship is often shallow, sometimes artificial, and rarely reflective. Little attention is given to worshiping with the mind. It produces people who have little depth or rootedness. They may develop a "zeal for God, but not according to knowledge" (Romans 10:2). They become worship junkies, searching for whichever church can supply the best rush.

This is Scarecrow worship: it would be better if it only had a brain.

On the other hand, some churches focus keenly on cognitive correctness. They recite great creeds, distribute reams of exegetical information, craft careful prayers ahead of time. And yet the heart and spirit are not seized with the wonder and passion that characterize those in Scripture who must fall on their faces when they encounter the living God. No one is ever so moved that she actually moves.

This is tragic because, as Dallas Willard writes, "to handle the things of God without worship is always to falsify them."

Those who attend such services may be competent to spot theological error, but the unspoken truth is they're also a little bored. Their worship is dry—it does not connect with their deepest hurts and desires. Rarely does it generate awe or healing, and never raucous joy.

This is Tin Man worship: if it only had a heart.

Some attempts to bring head and heart together have led not to the glimmering Emerald City, but to the Wicked Witch's forbidding dungeon guarded by drones. At times we've gotten it backwards, managing to combine in a single service the thoughtfulness usually associated with chandelier-swinging Pentecostals with the emotional expression of Scottish Presbyterians.