By Tom Ehrich

"Is Facebook harmful?" asked a blog, after Facebook users learned the social network had conducted a massive emotion-manipulation scheme.

Simple answer: Yes, of course Facebook is harmful. It's harmful in the same way an Interstate highway is harmful or Drano. If you tried to play kickball on I-95, or use Drano as a thirst-quencher, you would pay dearly.

Same with Facebook. Used properly and with caution, it serves some useful purposes. But used as a window on the world, a source of fact and objective news, a venue for meaningful friendship, or safe entertainment, Facebook is dangerous. Not only as a time suck, but as misleading, ad-driven, an anonymous snakepit where the disturbed prowl, and a place where your privacy counts for nothing and every detail about you is sold for profit.

In this way, Facebook is like most everything else, from family to church to employer to politics. It requires caution, savvy, an ability to learn from experience, and a healthy dose of skepticism about rosy claims.

Church, for example, has hurt more people than Facebook has ever imagined hurting. Yet it also does a ton of good, can make society better, stands occasionally and bravely for justice, and heals the sin-sick soul.

As much as we want to trust, we should be wary. Only God is fully trustworthy. The rest of us are like good old hoodie-wearing Mark: willing to do anything, try anything, sell anything, say anything to earn a profit.

If you can't stand being wary and eatchful -- as Jesus counseled -- stay home on Sunday and delete the Facebook app. Just don't get lost in magical thinking.