While the upcoming Christian-themed video game Left Behind: Eternal Forces is expected to be a big seller during the holiday season, at least one Wall Street expert thinks investing in the game's publisher could be a deadly sin.

MarketWatch columnist Chuck Jaffe has picked Left Behind Games as a "Stupid Investment of the Week."

Jaffe terms Left Behind Games (OTC: LFBG) "an interesting microcap stock," but adds that current valuations are "sketchy" and lack adequate financial data.

The analyst notes that LFBG has spent $12 million since 2002, but has yet to realize any revenue. That will change soon, of course, with the launch of the game. The company's own accounting firm says that it has "substantial doubt about (Left Behind's) ability to continue as a going concern."

Jaffe worries that small investors may be caught in a no-win position:

"...Left Behind is likely to be like many microcaps whose stocks pop after some good publicity, a hot conference, a new product or even a spam campaign. Its value is likely to fall back until it proves that it has more than just a good story... In that scenario, what will truly be Left Behind would be a lot of investment capital."