[From my final exam for Ecclesiology. I'm afraid I don't remember the question exactly. I believe my professor asked for an account of the vision of ecumenism given in Lumen Gentium. I have left it unchanged, except that one "mere" was changed to "very".]
In His ineffable providence the Triune God has established, in accord with that perfect plan which he made from all eternity and by which he antecedently wills the salvation of all mankind, the enduring mystical body of his Son our Lord Jesus Christ, true God and true man, who came to call sinners to repentance, to establish a new law of grace, to die in expiation for our sins, and to rise in greater glory as a sign of redemption and forgiveness and as the firstborn of that eternal life which we all, bound together in faith, hopefully await. This mystical body was established, by the common action of all three divine persons, as the light to reveal the inner life of the uncreated Godhead to the nations, so that all together might walk in newness of life, no longer bound by chains of sin but alive in hope and moved through the indwelling of the Holy Spirit to ever greater acts of Charity, being illumined through infused wisdom and inflamed through a prevenient motion on the part of the ineffable and glorious Godhead which enables mere mortals to call themselves true friends and adopted sons of the Most High. The truth, however, of this astonishing mystery of providence, of the condescension of the Lord of Hosts to empty himself and take on mortal flesh to the apparent degradation of His proper glory as eternal Word, the fact of our Lord's death at the hands of sinners, his betrayal for something as paltry as silver, his rejection for the sake of a thief and murderer, is so readily scandalous to the mind of man that our Lord proclaims to the disciple of John, "Blessed is he who is not scandalized on my account," acknowledging that a mind unsteadied by grace, unenlightened by faith, could easily and would in accord with its mere nature see in the very idea of such things an instance of the most deplorable and outrageous blasphemy. And thus, to deal directly with the problems of these latter days, to make clear to infidels, heretics, schismatics, those ignorant or confused or of false mind concerning the nature of this great light, this mystical body of Christ, the Church, we face a similar problem. For the heretics accuse us of idolatry and the heathens of idiocy; the schismatics see in our prelates the antichrist himself; and how can the proclamation of the truth in its many-varied richness be received among them? Will they not rather treat us like Joseph — stripping us of the fine subtleties and richness of our reflection, of the most excellent gifts of the Father which he has given in consequence of his particular love of the Son to clothe and adorn him in his ways and to make him known to those who behold him — will they not laugh at us scornfully and cast us into the depths to sell us off, exiles in another land, counted among the heathens and not the elect? Indeed, then we must approach them in humility of heart, not casting pearls before their swinish, cloven feet, but concealing the more delightful fruits of contemplation so as to avoid scandal — we must make ourselves simple as children, innocent as doves, so that in our simplicity the strong foundations of our faith can be made manifest and our Joy completed. For truly the foundation of their idolatrousness is mere clay, and it will shatter in time, but the glory of the Lord endures forever, which we are called to bear witness to after the fashion of Christ, who made himself low, who descended, so that ascending again he might draw all peoples to himself.
[My professor's comment: "F. Does not even address the actual question, much less answer it."]