All natural. No additives. No preservatives. These labels on supermarket products promise us that we'll eat pure, unadulterated food. What about consumers of the gospel overseas? Are they getting the pure, untainted message? Or are they getting a gospel loaded with American additives?

As I look back over nearly half a century of work in world missions, no question worries me more. My greatest worry is not about money for missions, people for missions, or the strategies and management of missions. It's about the contents in the package we label the gospel—the cure for people's sins—and whether we have administered the real medicine.

I once attended a study conference where missions scholars and executives wrangled for a weekend, trying to define the meaning of conversion. But I've never been to one where the gospel itself was addressed. We just assume we know. This can be a fatal assumption, especially for new missionaries.

Missions seminars come in 31 flavors, so to speak, but none of them focuses on the essential ingredients that make the "ice cream." Missionaries sell 31 flavors of the gospel overseas. Some flavors are denominational, some are not, but that's not the main issue.

In recent years, the uprising of consumers took dead aim on junk food: It looks good, tastes great, but—depending on the product—it either lacks essential nutrients, or it's packed with harmful additives. So it is with the canned gospel we stack the shelves of the world with. It can be packed with unbiblical additives: various rules and traditions to keep. Or it can be seriously deficient in life-giving ingredients: cheap grace, no repentance, no biblical foundation.

The results of consuming either kind of canned gospel are disastrous. ...