Amid the rising heat of the latest culture clash, a few people on both sides are finding calmer ways to engage, seeking to build bridges and even learn from one another. Some Christians, concerned that millions of Americans never cross the threshold of a church, want to understand why, as well as learn what it is in evangelistic efforts that turns people off. Some atheists, worried that polls show they are the least accepted social group in the country, want to break down stereotypes and change people’s attitudes.