Universalism occupies a middle ground between dogma and heresy. It is neither a teaching that all orthodox believers are expected to adhere to (in the way that the Trinity, or the union of deity and humanity in the one person of Christ are), nor one that they must avoid.
Perhaps the most appropriate category to employ is that of theologoumena. Theologoumena are pious opinions that are consistent with Christian dogmas. They are neither required nor forbidden.
To see universalism in the category of theologumena means that one cannot preach universalism as “the Christian view” or “the faith of the Church” but it also means that one may believe in it and develop a universalist version of Christian theology.
It is common for theologians to suggest that if apokatastasis is a matter of theologumena then, although one is permitted to hope that God will save everybody one must not go beyond this tentative faith to believe that God certainly will save all. Why? Because, it is suggested, to do so is presumptuous. I must politely disagree.
There are plenty of matters which are theologumena about which a believer may hold strong convictions. For instance, if universalism is theologumena then so is its denial, yet I have rarely heard it suggested that a firm conviction that some people will be lost forever is presumptuous or in some way out of order. Indeed most Christians throughout history have had precisely such a conviction and have felt at perfect liberty to preach it.
When I say that universalism, like its denial, is theologumena I mean simply that it is an issue about which Christians can legitimately disagree within the boundaries of orthodox Christianity. So whilst I have no problem with some universalists affirming no more than a hopeful universalism I can see no good reason to suppose that Christian orthodoxy requires such hesitancy.
Speaking for myself, I have no qualms about saying that I am a convinced universalist. I do believe that the proposition, “God will save everyone through Christ” is a true proposition and consequently I think that those who disagree with it are mistaken. However, what I don’t believe is that those who disagree with it (i.e. almost everybody) are unorthodox, unchristian, unkind, unspiritual, or . . . unclever.
Similarly, whilst I have never preached or taught universalism in a church context, if I were to do so I would not claim, “This is the Christian teaching” or “This is fundamental doctrine” or “This is the faith of the Church”. I would say, “This is an issue on which devout Christians disagree but here is what I believe and this is why I believe it. You must judge for yourselves, before God, what you think . . .”
So none of this is to suggest that the issue is a matter of indifference, nor that Christians should not debate about the issue—even vigorously. It is simply to relocate the discussion from being a debate between “the orthodox” and “the heretics” and to see it as an in-house theological disagreement. Indeed to see it as an issue that Christians, whilst they might disagree over it, should not divide over it.