If you are a Christian and want to serve Christendom well, you can start by not going out to eat—unless you're willing to love your neighbor the restaurant server as yourself.

Last week's story of pastor who instead of a tip left a snarky note for her waitress—"I give God 10 percent why do you get 18?"—made news because of what followed the otherwise commonplace event: a photo of the receipt was posted online and went viral, the server was then fired, and finally, after her stinginess found her out, the pastor issued a public apology.

But the initial incident? Ah, that's just the daily special, as anyone working as a restaurant server knows full well.

I experienced this dark underside of Christian culture while working my way through college as a waitress. My earliest waitressing years were at the kind of pancake joints where Christians love to congregate after Sunday morning, Sunday evening, and Wednesday evening services. The other servers and I always dreaded these shifts: the after-church crowd came in to "fellowship" more than, you know, eat, and that meant pushing together a lot of tables so they could camp out for a long time without buying much more than the endless cup of coffee. Not that any restaurant manager worth her salt would begrudge them that. My fellow servers called them the "Holy Rollers." Knowing there would be little, if any, tip left at the end of their meal, the servers saw the Christians' robust attempts at "friendliness" instead as pushy and arrogant. The memories still pain me now.

Decades later, my students who work as servers assure me that little has changed.

One says that in the steak house where she waitressed during college, Sunday lunch was the shift to avoid. Servers with seniority made the new people work it because "church people don't tip, don't control their children, and are really mean when you mess up their food," she says. On half a dozen occasions, a Sunday after-church group left her a tract instead of a tip. (Once, it was that tract that looks like money.) A few times, Christian customers told her that she should not be working on Sunday because it was the Lord's Day—while she was waiting on them.

Tipping isn't the only thing that makes some Christian bad witnesses in eating establishments. Alcohol is another. Many American Christians consider abstention from alcohol as a mark of strong faith—but some of these seem also to think that dramatic displays of that abstention in restaurants are a further sign of faithfulness.

One student tells me that when she waitressed, it was common for some customers to put all the wine glasses on their table upside down before a server even arrived there as if to say, "Don't even come NEAR me with that devil juice!" My parents once arranged to meet with church friends at a restaurant. Their friends chose the location because they refuse to patronize a restaurant that serves alcohol. Later, my mother wondered where they buy their groceries. And another student server tells this story:

One Sunday afternoon, I asked a lady, "What can I get you to drink today?" and she looked horrified and said, "I don't drink! I am a Christian, and it is Sunday, and my goodness it is 12:30 in the afternoon!" And after an awkward silence, her husband said, "I'd like a Diet Coke..."

There's more at stake here, however, than a few stiffed servers and some funny stories that inflate the sense of superiority of those telling them (present company included).

We know, from study after study, that religious folks out-give the general population time and time again. We know that Christians are among the most benevolent and philanthropic demographic groups. Something is at stake here more than mere stinginess.

Perhaps there are some simple explanations. Times are tough. Eating out is expensive. But if diners can't afford all of the expected expenses of eating out, they should go to an establishment they can afford, or not go out at all. Or perhaps in some cases, it's ignorance. Maybe some folks don't know that the minimum wage for servers is lower than for everyone else, or that the percentage for tips increases like everything else, or that the government collects income tax on tips, whether those tips are received or not. Tips aren't donations. Tips are payment for services rendered.

But my hunch is that what's really at the root of the bad-Christian-customer problem is bad theology.

It goes back, I suspect, to the unfortunate sway Gnosticism has had on Christianity since its early years. Gnosticism is a dualistic worldview that separates the secular and the sacred, the physical and the spiritual, elevating the spiritual and denouncing matter as evil. Under this view, giving one's money to support a Christian mission is seen as good, but spending money on earthly pleasures—like eating out—while not necessarily bad, isn't quite as good.

This Gnostic influence on the church can be seen in much more insidious ways than in poor restaurant behavior (for example, in thinking of the role of pastor as a "higher calling" than that of, say, an accountant), but spotting and correcting such heresies often begins with the small things.

I don't think that Paul had servers in mind when he exhorted believers, "So whether you eat or drink or whatever you do, do it all for the glory of God," but the principle certainly does apply. Those who are to represent Christ in all they do should remember that includes paying the check—in total—at the end of the meal.