Like all too many Americans, Mark Almlie was laid off in the spring of 2009 when his workplace downsized. He has been searching for an appropriate position ever since, replying to more than 500 job postings without success.

But Mr. Almlie, despite a sterling education and years of experience, has faced an obstacle that does not exist in most professions: He is a single pastor, in a field where those doing the hiring overwhelmingly prefer married people and, especially, married men with children.

Mr. Almlie, 37, has been shocked, he says, at what he calls unfair discrimination, based mainly on irrational fears: that a single pastor cannot counsel a mostly married flock, that he might sow turmoil by flirting with a church member, or that he might be gay. If the job search is hard for single men, it is doubly so for single women who train for the ministry, in part because many evangelical denominations explicitly require a man to lead the congregation.

Mr. Almlie, an ordained evangelical minister who lives in Petaluma, Calif., has also had to contend with the argument, which he disputes with scriptural citations of his own, that the Bible calls for married leaders. “Prejudice against single pastors abounds,” Mr. Almlie wrote in articles he posted on a popular Christian blog site in January and February, setting off a wide-ranging debate online on a topic that many said has been largely ignored.