Sincere Worship (Ecclesiastes 5:1-7)

It is easy for us as Christians to think that the people outside the church are really bad people while we are the good or moral people.  The preacher in Ecclesiastes wants us to be careful of such a position because within the community we might worship the Lord, but we might not really be worshipping the Lord.  What is the problem of living this way?  How does making such a show of piety without true heart conviction present a problem?  How can this be a functional atheism when we are worshipping the Lord?