For those of us who have spent countless hours going to church, it's hard for us to contemplate that there is a possibility that what we have called worship might not be considered worship in the eyes of God. He speaks to us in His word that He is seeking the "true worshippers",  who worship Him in spirit and truth. Why would He be seeking true worshippers when all He would have to do is to stop by any local church on a given Sunday?
Jesus came to die for our sins and to crucify the flesh that we might no longer be slaves to sin. Yes, we are a new creation but we still have to deal with our flesh on a daily basis. Our flesh and the spirit that we've been given are in opposition to one another. We are called to put no confidence in the flesh but we are to worship in spirit and truth. To attempt to worship our God with our flesh is to corrupt our worship with something Jesus crucified on the cross. 
What's born of the flesh is flesh and what is born of the spirit is spirit. God is spirit and our flesh has no part in our worshipping Him. 
Let's open up the gospel and discover how we are to be a true worshipper!