This is certainly a profound, well written work. One can tell that Guder has thought long and hard on this, and has reflected as well on many others' reflection.
Here he presents the case against the Western Christian church which he feels has succumbed to gosepl reductionism. By this, he means when Christians reduce the gospel in all its fulness and mission to a controllable, manageable level. Pertinent to this understanding is this quote: "We are constantly tempted to assert that our way of understanding the Christian faith is a final version of Christian truth."
He resonates to the freeflowing tension always seeking to move Christianity along unknown paths, ever broadening and deepening its hold on humanity. Reductionism as he defines it severly restricts it as it diminshes what for him is vital and called its "incarantional witness." Here he refers to God's grace reaching out in a Christian's call and vocation.
He appears to drift back and forth from orthodoxy to something far from it, especially evidenced by his continued reference to ecumenism as being important and vital element in the repentance and continual conversion needed by Christianity. Although he speaks at length passionately about Jesus and the cross, he severely reproves the church for focus on salvation of individuals.
By continual conversion he refers to a rather liquid, dynamic movement in Christianity without boundaries, yet constantly refining what institution is already there. When Chrisitans becomed concerned about maintenance, then mission is lost. Continual conversion refers to this movement back to mission.
In many cases on many ecclesial and theological issues, he advocates a moderate position, but this only appears to be one mitigated by his resolve to movement from within existing ecclessiastic structures, rather than disbandonment and new ventures.
There is much to be contemplated in this writing that is worthwhile to reflect on even if one is not of the author's theological posture or without accepting his proposed remedies. Although careful to provide definitions, what is omitted from them and what is taken back at places where one felt good was given must be carefully discerned.