For my Systematic Theology III course, I had to read Hans Schwarz, Eschatology (Grand Rapids: Eerdmans, 2000). I found the book generally well-written and -researched, but his treatment of universalism is not sympathetic or very charitable at all. His arguments contra are not convincing.
In a discussion of the final judgment, he notes that there is an apparent paradox between God's love and justice as displayed in the judgment. For the New Testament also contains many assertions that God wants all people to be saved (p. 395), in spite of the apparent affirmation of a two-fold outcome of this judgment (pp. 394-5). He cites from Rom 11.32, God has imprisoned all in disobedience so that he may be merciful to all, and 1 Tim 2.4, [God] desires everyone to be saved and to come to the knowledge of the truth.
The first problem, however, and this is a noticeable one in his earlier discussion of universalism as well (pp. 337ff.), is that there are also texts which speak not only of God's desire to save all persons, but of the eventual realization of this fact. Rom 5.17-9 stand as the paradigm case: For if, by the trespass of the one man, death reigned through that one man, how much more will those who receive God’s abundant provision of grace and of the gift of righteousness reign in life through the one man, Jesus Christ! Consequently, just as one trespass resulted in condemnation for all people, so also one righteous act resulted in justification and life for all people. For just as through the disobedience of the one man the many were made sinners, so also through the obedience of the one man the many will be made righteous. He does not even consider these texts, though these are regularly brought forth in discussions by universalists themselves (e.g., Thomas Talbott, The Inescapable Love of God; Gregory MacDonald/Robin Parry, The Evangelical Universalist). He likewise does not consider the problem that if God's express goal is to unite the whole creation in salvation, then a failure to accomplish that goal amounts to a compromise of his sovereignty.
Beyond that, moreover, his attempt to resolve the paradox itself is both self-defeating and ultimately unbiblical. Schwarz ultimately appeals to the transcendence of God to undermine the paradox:
The solution must rather be sought in what we mean when we talk about the justice and love of God. Do we really mean that we describe God with these terms, or do they not rather disclose certain aspects for God for us? We must remember that God's self-disclosure to us can only be expressed in human language, and this means with necessarily anthropomorphic and inadequate conceptual tools. Thus we can rightly conclude that God is beyond justice and love, just as he is beyond being a person when we call him a personal God. . . . Even in our most sincere concern for [the eternally lost], we have to acknowledge the ultimate hiddenness of God, a God who is beyond justice and love. At this point we can only hope without knowing for sure that his never ending grace will ultimately prevail (pp. 396-7).
This, as I say, is incoherent as a defense of hell. For if God transcends our ascription of "love" to him, and so therefore we justify hell and solve the paradox, why does he not also transcend our ascription of "justice" to him, in which case it is not obvious why hell must be eternal? The proposed solution to the paradox undermines itself in that it fails to justify an eternal hell by its own terms. More than that, if God transcends justice, then why is there talk about a judgment, and an inevitable one? Why may we be sure that justice will prevail, that judgment is inescapable, but that love may not ultimately win? Why the asymmetry?
Schwarz desires to uphold what he sees to be a biblical tension and paradox, but his proposal is ultimately unbiblical, to my mind. His notion that God transcends our ascription of justice and love to him seems plausible enough, but he leaves us with no conceptual "center" by which to understand God. The bible itself, however, is not so pluralist; it attempts to define God, and it names his essence as love (1 John 4.8). The bible says that God is holy, but never names him holiness; it affirms that he is just, but it doesn't title him Justice; but in light of the central and definitive revelation of God in Jesus Christ (cf. John 1.18; Heb 1.1-3), the bible does name him not only as loving, but as Love. This is the "center" of God, this is the biblical language that best appropriates the ineffable nature of God. Schwarz therefore goes against the bible in attempting to defend it, when he says that God is beyond love and justice alike, tout court. We may grant that God is beyond our language, but love is the word we have been given to define him most succinctly. Therefore the "paradox" must be resolved in the direction of love.