food for thought
There's a funny post on Stuff Christians Like today about "Witnessing to people that don't believe the Bible using the Bible." (How many times have I seen this? More than I can count, especially in my teenage years, where at least 2 of our 6 youth ministers were obsessed with getting us to prove to our agnostic classmates that evolution never happened.)
Anyway, the humor in SCL touches on an interesting thought someone sent in on Andrew Sullivan today: the idea that eternity is not necessarily an appealing thing.
In both of these cases, one humorous and the other not so much, the person of faith is trying to sell his belief on a basis of thought patterns that his target doesn't share. Put another way: if you're trying to sell someone on Jesus by appealing to their desire for "eternal life," you may be speaking the wrong language.