If I could impress on Young, Restless, Reformed students just one word of friendly counsel to address what I think is the most glaring deficiency in that movement, this is what it would be: "Brothers, do not be children in your thinking. Be infants in evil, but in your thinking be mature" (1 Corinthians 14:20).

I'm very glad the ranks of YRRs are growing numerically. Many good things about that movement are full of promise and potential. In order to fulfill that potential, however, this generation of Reformers desperately needs to move past the young-and-restless stage. Immaturity and unrest are hindrances to spiritual fruitfulness, not virtues.

When Paul told Timothy, "Let no one despise you for your youth" (1 Timothy 4:12), he wasn't suggesting that Timothy should forbid people in the church to disapprove if the pastor were to display immaturity, juvenile misbehavior, youthful indiscretion, or other traits of callow character.

Much less was the apostle suggesting that Timothy should cater exclusively to young people while purposely marginalizing the elderly. That, I'm sorry to say, is the kind of advice we sometimes hear nowadays from many self-styled church-growth experts: Pastors must be innovative, stylish, agents of change. You have got to appeal to young people. They are the only demographic that really matters if the goal is to impact the culture.

And if elderly people in the church prove to be "resisters," just show them the door. Give them the left foot of fellowship. After all, "There are moments when you've got to play hardball."

But for heaven's sake don't dress for hardball. HCo. clothes and hipster hair are essential tools of contextualization. The more casual, the better. Distressed, grunge-patterned T-shirts and ripped jeans are perfect. You would not want anyone to think you take worship as seriously as, say, a wedding or a court appearance. Be cool. Which means (of course) that you mustn't be perceived as punctilious about matters of doctrine or hermeneutics. But whatever you do, do not fail to pay careful attention to Abercrombie & Fitch.

I sometimes think no group is more fashion-conscious than the current crop of hipster church planters—except perhaps teenage girls.

But, someone protests, Scripture does say, "Let no one despise youthfulness."

We frequently hear that text cited to make that argument. But Paul's point to Timothy was precisely the opposite: Don't give anyone a reason to criticize you for being immature, "but set the believers an example in speech, in conduct, in love, in faith, in purity." Paul was not suggesting that Timothy should exaggerate his youthfulness or wear it as a badge of distinction; he was urging the young pastor to cultivate maturity beyond his years.

Charles Spurgeon understood the principle. He became pastor of London's largest and most famous Baptist congregation at the age of 20, less than five years after his conversion. But he consciously and diligently sought to display maturity beyond his years—especially in his manners and his approach to ministry. At age 40, he reflected on the brevity of his own adolescence: "I might have been a young man at twelve, but at sixteen I was a sober, respectable Baptist parson, sitting in the chair and ruling and governing the church. At that period of my life, when I ought perhaps to have been in the playground . . . I spent my time at my books, studying and working hard, sticking to it."

As I have shown elsewhere, evangelicalism's childish fascination with teenage fashions, milk rather than meat, and trivial entertainment rather than serious doctrine is deeply rooted in a pragmatic ministry philosophy. It is not "Reformed" in any sense but is a classic expression of man-centered free-willism—what Colossians 2:23 refers to as "self-made religion." It is the antithesis of the Bible's emphasis on the sovereignty of God and the unadulterated gospel as the power of God unto salvation. Instead, it begins with the assumption that the lost must be won by sheer gimmickry—through the cleverness of human ingenuity or the supposed appeal of worldly fashion.

That, of course, is precisely the philosophy Paul rejected and refuted in 1 Corinthians 2:1-5.

One might think any movement that formally affirms Reformation doctrine would be at the vanguard of opposition to the jejune faddishness that has plagued evangelicalism for the past few decades. But that has not always been the case with today's Young and Restless Reformers. As the YRR movement has taken shape, some of the best-selling books and leading figures in the movement have been completely uncritical (and in some cases openly supportive) of seeker-sensitive-style pragmatism.

Worse, the fads and gimmicks some prominent YRRs seem to want to be known for are much more sinister than the shallow diversions that seeker-friendly churches were playing around with twenty years ago. Judging from certain church websites and pastoral blogs, a sizeable core of young men in the YRR movement are perfectly happy to give the world the impression that cage fighting, beer-drinking, cigar-smoking, hard-partying, and other forms of bad-boy-behavior are the distinguishing marks of their religion. Meanwhile, many others who identify with the movement evidently think any talk of holiness—not to mention any concern for taste or propriety—is tantamount to the rankest sort of legalism.

Such an opinion reflects a carnal immaturity that must not be encouraged. When smutty talk and lascivious subject matter from the pulpits of 40-year-old pastors are routinely defended by an appeal to the "youthfulness" of the offender, someone's maturity meter is badly askew. It is a serious problem. The movement cannot survive or prosper under leaders who are stuck in perpetual adolescence—no matter how much they talk about manhood and thump their chests to demonstrate their machismo.

Those who exhibit such behavior are out of their element claiming to be Reformed. Maturity is a necessary virtue for those who would be truly effective in ministry. "Solid food is for the mature, for those who have their powers of discernment trained by constant practice to distinguish good from evil" (Hebrews 5:14). That is a desirable—and honorable—goal: Strive for it.

"Not that I have already obtained this or am already perfect, but I press on to make it my own, because Christ Jesus has made me his own. Brothers, I do not consider that I have made it my own. But one thing I do: forgetting what lies behind and straining forward to what lies ahead, I press on toward the goal for the prize of the upward call of God in Christ Jesus. Let those of us who are mature think this way" (Philippians 3:12-15).