Why both right action AND right belief matter

In response to the action taken  by the United Church of Canada against the self-proclaimed Atheist minister Gretta Vosper, a blogger named Christian Chiakulas wrote that their decision to defrock her for her beliefs (technically, lack of any belief) is why mainline denominations are dying.  The full blog post explains his position, but in a nutshell it appears that he thinks that judging someone for his/her beliefs is wrong and that only our actions matter.  In the post Chiakulas quotes an author named Roger Wolsey as saying, “[Progressive Christianity] emphasizes orthopraxy instead of orthodoxy (right actions over right beliefs); embraces reason as well as paradox and mystery — instead of blind allegiance to rigid doctrines and dogmas…and does not claim that Christianity is the only valid or viable way to connect to God.”  While this may fit the definition of Progressive, it certainly doesn't fit any historically relevant definition of Christianity.  And that is the whole point, what we're dealing with here is an attempt to redefine Christianity by refusing to define any belief, or lack thereof, as being out of bounds.  In other words, progressives like Chiakulas and Wolsey want to remain a part of Christianity whether or not they believe in Christ, whether or not they believe in God, and whether or not they believe in the Gospel, belief evidently has nothing to do with it.
To accept the notion that right belief doesn't matter you have to surrender to two fundamental presuppositions both of which are extremely dangerous and both of which are anathema to what the Church has been and stood for during the past two thousand years.  The first premise is this: There is no such thing as Truth with a capital T.  All truth must be relative, the Bible must be a collection of stories, not a revelation from God.  If there really is an absolute Truth, it would certainly matter whether or not a person embraces or rejects it, so Truth has to go.  The second premise: That mankind is inherently good.  If right behavior is all that matters, mankind must be capable, on his own, of being good.  This however flies not only in the face of human history, but of the explicit teachings of the Bible.  We cannot possibly please God, on our own, simply by doing what is right, because our very nature is sinful and we cannot fellowship with a holy God until we are reborn in Christ.  
Lastly, in his blog post, Chiakulas claims a remarkably stunning thing, "Jesus welcomed everyone who was willing to follow “The Way.”  Everyone.  And there was no religious test to becoming an apostle, other than a willingness to forsake all for the Kingdom of God."  What Chiakulas is failing to understand is that the disciples whom Jesus called to follow him were already believers in the God of Abraham, in the LORD, they already believed.  That Jesus allowed them to follow him until they saw that he was the Son of God, instead of requiring it first, was certainly not an affirmation that such a affirmation must come from them eventually.  That this claim of Chiakulas can be refuted by Jesus' own words, easily, ought to prevent someone from claiming it about how he conducted himself, but here it is.  If Jesus cared so little about what his followers believed, how could he say to them, "I am the way and the truth and the life.  No one comes to the Father except through me." (John 14;6)  And how could John end his Gospel with, "these are written that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name." (John 20:31)  The list of Biblical quotes that utterly refute such an asinine assertion that Jesus didn't care what his disciples believed, could go on and on and on.  
What we belief absolutely matters, for as anyone remotely familiar with the writings of Paul knows, it is by grace we are saved, not by our works, when we call upon the name of the Lord.