Goodwin: "No sin troubled him but their unbelief"

The doyen of Puritan theologians, John Owen, is reported as having said:
"The greatest sorrow and burden you can lay upon the Father, the greatest unkindness you can do to Him is not to believe that He loves you."
Unbelief. It's regarded by most of us who would call ourselves 'believers' as a minor flaw, an understandable weakness, a trivial aberration, an insignificant sin. It seems we were wrong.  

My attention was recently drawn to a recent reprint of Puritan Thomas Goodwin's The Heart of Christ. In a section in which the author highlights examples of Christ's tenderhearted affection towards his disciples in his post-resurrection appearances to and conversations with them, Goodwin also notes the instances and reasons for Jesus reprimanding them at this time. Does he chide them for their disobedience, that they betrayed him, or that they forsook him? No. Rather, he says, "How foolish you are, and how slow of heart to believe ..." (Luke 24: 25 NIV; also v 37-41).  Upon which Goodwin profoundly and disturbingly comments: "No sin troubled him but their unbelief. Which shows how his heart stands, in that he desires nothing more than to have men believe in him; and this now when glorified." (p.32f).

Hold that thought, and then consider Dr Jack Miller's indicting diagnosis, that many - if not most - of our churches are being paralysed or are spiritually suffocating through vibrant 'unbelief'.
Acknowledging the insights and practical help of many recent books to encourage and instill evangelism and disciple-making as core elements within church life, nevertheless, Miller's assessment is:

"Having acknowledged the value of these works, I yet insist that there are crucial elements in the faith of the local church and its leadership that cry our for correction. I am convinced that many congregations and their leaders are immobilized by unbelief that concepts for ministry that would be helpful in other circumstances are relatively valueless to them (Outgrowing the Ingrown Church, p.16).
"...We have surrendered our hearts to the familiar forms of our religious life and found comfort of soul, not in knowing God, but in knowing that our worship services are firmly settled and nothing unpredictable will happen on a Sunday morning. Thus we have lost contact with the risen Christ as the source of our spiritual life, and what is worse, we are so often enfeebled that we hardly know that we are out of touch with the King. In the local church we are busy, separated from Christ's transforming presence... (p.19f)
"...I believe that it is right here that we encounter the essence of the threat to the modern congregation: its tendency to despair and defeat because it has redirected its faith toward its past or to human resources, rather than to the promises of God with their focus on the power of the Spirit to revive us." (p.24)