In 1977, the Dr Pepper soft drink was promoted with the slogan, “Be a Pepper.”
The marketing campaign behind that slogan had television commercials with hip, cheerful, attractive people dancing through life with the lines,

I’m a Pepper, he’s a Pepper,
She’s a Pepper, we’re a Pepper,
Wouldn’t you like to be a Pepper, too?
Be a Pepper. Drink Dr Pepper.

Parody
A few years later, the Saturday Night Live sketch comedy TV show did a skit* with Laraine Newman playing a teenage girl named Jennifer, sitting on the floor in the family room with the telephone. She calls up strangers from the phone book and encourages them to drink Dr Pepper and asks, “Wouldn’t you like to be a Pepper, too?” She gets the polite brush-off that you’d expect from such a marketing call.
After listening to a few of these calls, her parents tell her that she’s changed ever since she became a Pepper. She’s always at Pepper meetings or calling strangers on the phone or going door to door to encourage people to drink Dr Pepper. She doesn’t see her old friends anymore.
After the father says that it would be different if she got paid, she says, “A Pepper would never accept money for this!”
It’s like she’s in a religious cult. What could be crazier? We have consumers of a commercial product spending their own time and resources increasing the sales of that product, with the only compensation being accolades from fellow believers or perhaps just the knowledge that important work had to be done, and they pitched in to help.
Christianity
We’re more familiar with earnest evangelists within Christianity, but that doesn’t make them any more sensible. They’re told to get out and increase Christianity’s market share, and many do it without pay. Does this make any more sense than Jennifer’s project?
Would you be motivated if the paid staff of Dr Pepper encouraged you to spread the word? Why be any more motivated if the paid staff of the Catholic church or Baptist church or Lutheran church made the same request?
The Great Commission
The typical response is that Christians are obliged to spread the word, but average Christians shouldn’t flatter themselves that Jesus gave them the Great Commission. The gospel of Matthew ends with the eleven disciples at an offsite with Jesus. Jesus said, “Go and make disciples of all nations” (Matthew 28:18), but this was clearly addressed to those eleven disciples.
To Christians who think that evangelism is important, remember that it was important to Jennifer, too. Is your project any better supported by logic?
See also: “The Great Commission and How It Doesn’t Apply to You”

Satan deceives us into voluntarily laying aside 
our best weapons of logic and evidence, 
thereby ensuring unawares modernism’s triumph over us.
— William Lane Craig, Reasonable Faith

* The skit is from s5e16 on 4/12/80. The video is here (skip to 49:00), but Hulu Plus is required.
(This is an update of a post that originally appeared 7/17/13.)
Image credit: Ben Sutherland, flickr, CC