Righteousness -- Christ's or your own?

I've been listening to Tim Keller's RTS class on Preaching Christ (available on iTunes U). He points out that if Christ isn't our "righteousness and sanctification and redemption" (I Cor. 1:30) then something else will be. That's true for the religious person as well as the irreligious person -- and those of us who have a propensity for both at various times in our lives. The religious person may substitute going to church three times a week and having quiet time each morning, while the irreligious person may substitute going to the gym each morning. The environmentally aware person may consider shopping at Whole Foods their "righteousness" -- and I'm someone who enjoys shopping at Whole Foods! One can see how buying organic and "going green" has become a quasi-religion for many. I don't care how secular you think you are, all of us are born hard-wired for religion. Keller's underlying point is that the Christian gospel of justification by faith alone in Christ alone is pitted against both religious works-righteousness and irreligious works-righteousness. At bottom they're both attempts at self-justification. Everyone, whether they've thought about it or not, is striving for some sort of righteousness. The question then becomes, is it the righteousness offered in Christ? or one of your own creation?