A term coined by Buddhist author A.L. de Silva in his book Beyond Belief: a Buddhist Critique of Christianity.
He says that Fundamentalist Christianity poses a threat to Buddhism, and it can only be countered by familiarizing oneself with its teachings and fallacies.
A Westerner may be surprised by the idea of the threat to Buddhism. After all, in America many people turn away from Christianity to embrace Buddhism.
But the author published his book in Sri Lanka. The fundamentalists are actively proselytizing in many traditionally Buddhist countries, where many Buddhists are Buddhists simply because Buddhism was passed on to them by their ancestors, not because they necessarily even know the basic tenets of Buddhism.
At any rate, according to the author taking up the challenge can be only beneficial: If one studies both Christianity and Buddhism in depth and objectively, the challenge poses no threat.
Obviously, many Westerners, not necessarily Buddhists, feel the threat, as can be seen by the sheer number of write-ups about Christianity here on E2.
My personal advice to them is: