The Church has been complicit in teaching that there is no propriety to dress. We used to dress to the nines on Sunday morning. In the 1960's, that began to change - students and surfers and Jesus freaks began turning up at church in jeans and sandals. That's all well and good - I'm not suggesting the church copy five-star restaurant and post a maître d' at the door to hand out jackets and ties to men who show up in T-shirts. Everyone, even those who disdain or can't afford spiffy suits, should be welcome in church. But perhaps we have erred on the side of casual. I've noticed that I worship differently when I'm wearing more formal, fancy clothes. I'm more inclined toward reverence. I'm readier to meet a king. The prayers I pray when I'm wearing my pj's are, not surprisingly, often more intimate, and there is a place for pj prayers - but that place may not always be church. We Christians in our institutional churches so want people to come worship with us on Sunday morning that we hesitate to impose a dress code upon them. And yet what appears welcoming, what seems hospitable, may in fact be a failure. It's God, after all, that the people are coming for, and helping them dress appropriately may be part of preparing them to meet Him.
-Lauren F. Winner, Real Sex: The Naked Truth About Chastity, pg 76-77