Excerpts from The Davenant Institute’s  Beyond Calvin: Essays on the Diversity of the Reformed Tradition (underlining mine):
 This is not an unfailing or unqualified endorsement of the Davenant Institute, nor a promotion of it as an institution composed of true Christians. They do appear to be a reputable resource for accurate historical information representing the damnable Reformed Tradition.
“Bucer is one of the central figures in the oft-rehearsed debate amongst Protestants about the true marks of the church [….]The debate happened around a proposed third mark of the church: the practice of church discipline.”
“This synthesis of Erasmian humanism and Lutheran soteriology would become a hallmark of the Strasbourg reformer’s thought.”
“This reputation for tolerance, or to use Erasmus’s term, harmony, is, in fact, part of what drew Bucer himself to the city [of Strasbourg].”
“Bucer would strongly defend this understanding of the church. In the letter he wrote, ‘We are often too lenient towards those who agree with us and accept our teaching and too severe toward those who dissent and do not yet accept our teaching.'”
“Luther did not resort to violence against [heretics] directly. By 1525 he had driven Karlstadt [and] Munzer…out of Wittenberg and he had refrained from calling for their deaths. Yet when it came to rebellion rather than heresy, Luther was willing to contemplate violence…and to call for the slaughter of the peasant rebels whom he compared to rabid dogs. Zwingli took a harsher approach. By 1525, under his leadership, the city of Zurich was aggressively harassing those who refused to accept infant baptism. And in 1527, when adult re-baptism was declared a capital crime, the execution of anabaptist heretics became routine. The first of these martyrs, Felix [Munz or Munst?–CD] was drowned in Lake Zurich — a fitting punishment, according to the Zwinglians, for someone who abused the waters of baptism…ironically, but logically, martyrdom confirmed for them their identity as the true Church of Christ…a most painful self-fulfilling prophecy” (Carlos M. N. Eire, Reformations: The Early Modern World, 1450-1650; my transcription of the audiobook version of this work–CD).
“Bucer was ready to admit that this broad definition included Catholics: ‘there are many who belong much more to Christ among those who are considered papists than among those who seem to be evangelical.'”
Bucer’s “broad definition” of essential gospel doctrine boiled down to the following:
‘Christ is the unique savior of mankind, true God, true man, from whom we await all things.’
Thus Bucer did not know or believe the true gospel of Christ who is actually a Just God and a Savior, not the “try-and-fail savior” of Roman Catholics and moderate and “‘well-meant’ offer” Calvinists.
“…the church has a great deal it is expected to do in helping people to truly follow Christ by embracing Christian discipline. This has the effect of making the church both far more important in individual spiritual formation and far less pervasive within the public square since Bucer expects Christian magistrates, rather than Christian ministers, to do much of the large-scale cultural work needed to produce and protect a broader Christian society.”
“The centerpiece of Bucer’s approach is patient, irenic discussion done with the goal of preserving Christendom by helping more nominal or confused Christians take up the yoke of Christian discipline. Understanding this point helps to explain Bucer’s approach to Marpeck.”
I don’t know who Marpeck is (presumably an Anabaptist), but one wonders who the “confused Christians” are. How about Nestorians or Arians? Or would that be “too irenic,” even for the broadminded Bucer?
[Note: The God-hating Roman Catholics hold to an “orthodox shell” of the Trinity and the Incarnation and Deity of Jesus Christ, but when the Hammer of God’s Word cracks open this husk the damnable kernel inside is revealed. The “damnable kernel” is its theological definition and exposition, which includes such Christ-denying doctrines as Universal Atonement, Purgatory, the Mass, etc.]
“Bucer sees church discipline and unity as being closely related — the goal of discipline is love. When the body is splintered such that discipline cannot be practiced coherently within the church, that goal is compromised.”
Would it be loving to discipline those at Westminster Abbey who spent years arduously hammering out the facinorous fiction “as if the offending party were dead”? Would it be an instance of splintering to discipline the framers of the Westminster Confession for strengthening the hands of adulterers with such a fanciful phrase?
“It is here, then, that we see Bucer’s sharpest departure from the later proponents of the third mark of the church. Whereas the radicals and later the Presbyterians of England would be marked by a sort of precisionist spirit that demanded full doctrinal purity before union could be assumed and joint work done, Bucer embraced a broadly irenic style of faith that sought common cause not only with radicals, but also with Roman Christians. Bucer’s ecumenism, if we can use that term, was never unprincipled or lacking in theological roots. The goal was the promotion of Christian love within local churches and Christendom more broadly. Discipline served that goal. For Bucer the work of Christian reconciliation and Christian discipline are not only not at odds, they are one and the same.”
Thus Bucer is a principled and promiscuous whore who commits spiritual fornication with just about every passer-by, under (nearly) every green tree.