OK, the Lions got beat up 37-13 by Chicago. It's not the end of the world though, I think it was nothing more than a bad game. Let's consider a few things:
The defense held their own. Of the 37 points, 21 came from interception and punt returns. Most of the remaining 16 came from the Bears having a short field. The overall effort and play of the defense was very good. They limited Forte's impact, they got to Cutler, and they covered pass routes well.
The offense turned the ball over six times. This is an uncharacteristic fluke, not a trend. Up until this game, the Lions had the fewest turnovers in the league. Two of the turnovers were flukey fumbles and some of the picks were due to Stafford being inexperienced in weather games. Plus, when the offense wasn't turning the ball over, they were doing a pretty good job of moving it against a solid defense.
Lastly, the Lions are still a game up on Dallas and Atlanta and tied with Chicago for the WC. There's a lot of football left to be played and Detroit still has 4 home games remaining. Plus, the second half doesn't look as tough as it did a month ago. They still have a good shot of making the post season.
Overall, there are still a lot of reasons to be optimistic about the Lions.