You're far from the only one who doesn't take Atlanta seriously, but what else is new, every time they say "this is the game that will show that the Falcons are for real", but even after shutting down both Mannings, Brees, RG3, Romo, Rivers, Stafford, it will always be next game that matters until they win a Superbowl (and even then will probably be called a fluke

).
What exactly do you not take seriously? A team that is 33-4 at home under Ryan, the best 3 targets in the business in Roddy, Julio (who torched Seattle's big corners last go round for 205 yards BTW) and Gonzalez, a QB who's on the fringe of being elite and shown a great ability to come from behind and be at his best when his back is against the wall, or a defense who is top 5 in both scoring defense and turnovers (bend don't break). This isn't last year's Falcons, they have 2 new coordinators with a much more aggressive attitude.
And the scary thing is that they haven't even shown that much yet. I truly believe that they haven't been running so much no-huddle because they haven't had to, and don't want to give them film on it, but Ryan is one of the best in the biz at dictating tempo and switching plays at the line to exploit the defensive looks. Kroy Biermann also said recently that DC Nolan's playbook is much deeper than they've shown. That should scare offenses with how well they've already done to not allow a lot of points.
The one thing this team doesn't do well is run, but they've been the best in the NFL in the screen game, which both helps to supplant the run and combat the pass rush.... As for the pass-rush, the Seahwaks having Clemons out is a big blow, and it might even help the Falcons running game with Irvin being a big liability against the run (he's purely a pass-rush specialist, but will be forced to start).
The keys for the Falcons will be stopping Lynch (have not been very good against the run, but this same unit was top 10 against it last season) and making Wilson uncomfortable (more confident about this, with Nolan always disguising looks and moving guys around).
Should be a hell of a game, but especially playing in the Dome and not Seattle, it's ridiculous that the Falcons are getting so little respect. That should change on Sunday, win or lose.