There is definitely an issue with church-goers here in America. It is unfortunately true that a majority of church-goers lives don’t look much different than the rest of the world. However, to call someone "born again" simply because they go to church or because they call themselves a Christian is a huge mistake and distorts the biblical meaning of the term “born again”.
Read what John Piper had to say about it:
Now I want to say loud and clear that when the Barna Group uses term “born again” to describe American church-goers whose lives are indistinguishable from the world, and who sin as much as the world, and sacrifice for others as little as the world, and embrace injustice as readily as the world, and covet things as greedily as the world, and enjoy God-ignoring entertainment as enthusiastically as the world—when the term “born again” is used to describe these professing Christians, the Barna Group is making a profound mistake. It is using the biblical term “born again” in a way that would make it unrecognizable by Jesus and the biblical writers.Read Piper's entire sermon here
If Barna was truly able to identify real "born again" Christians, I think the results of this study would be profoundly different.