Well, yes, Leo.  But the problem lies in defining "what is true".  And if the constitutional Church says that truth is what is declares to be truth, then there is no more conversation.  Unless one is willing to concede that human understanding of Truth grows with time and that the understanding needs to be revisited and revised periodically, then we are basically stuck.  
I fail to understand how any person who considers Truth to come from God and believes God to be infinite, all-knowing and all-transcending can possibly believe that any group of human beings,  regardless of how closely they try to follow the guidance of the Spirit, can conceivably claim to know the Truth.