In the life of the early church the confession of faith was, "Jesus is Lord!" However, as the years progressed statements of faith became increasingly detailed. After the Protestant Reformation, group after group wrote its own distinctive confession. One primary example of this is the Westminster Confession of Faith (among many, many others).
As I look around the Christian landscape, I see a significant problem with these lengthy statements of faith. The problem is that they leave no room for a person to change his mind on an issue. Let's say a Christian says that he agrees with a certain statement of faith. Later, upon a further study of scripture he changes his mind on that issue. Uh-oh. What is he to do? This would be no big deal; however, many local churches require their new members to agree with their specific statement of faith. If this Christian no longer agrees with that confession, does he then have to withdraw his membership?
This, of course, brings up the problem of "membership" in a local body of believers. That's for another day.
To sum up: lengthy statements of faith allow no room for believers to change their minds on an issue. In this way, they actually discourage bible study and the asking of hard questions. The body of Christ would be much better off by simply sticking with "Jesus is Lord!" as our confession. Christ is all we need, and that statement is all we need.