Capitalism/Consumerism gives us purpose. To consume and acquiesce as many goods and services as we can within our short lifespan is our goal. Boredom is our enemy. Society creates more devices which we create and consume to combat our boredom. Traditional values - like thriftiness, modesty, and self-restraint have been generally abandoned and replaced by greed (which is what drives captialism). Cultural symbols like Christmas and Easter have been commercialized to reflect our new views. Biblical "facts" about our world (earth center of universe, creationism, etc.) have been replaced by scientific "fact".
Is this new purpose any worse than the one given by Christianity? That depends on whether or not God exists. Better yet, I think it depends on whether or not you believe you are leading a more fufulling life with consumerism or christianity. It's not that you can't believe in both, it's just that our society is slowly replacing mainstream christian values with consumerist ones. We are at a point where there is a transition occouring, and many people (including myself) are trapped in some sort of limbo not knowing which one to believe.
If you really want to know what I mean, pick up a copy of Technopoly by Neil Postman or A Brave New World by Aldous Huxley.