Apart from Clement of Alexandria, Origen, Didymus the Blind, Gregory of Nyssa, Theodore of Mopsuestia and Isaac of Nineveh (maybe I forgot someone) there are few writers of whom we can conclusively demonstrate that they firmly held to universalism. Many were open to the possibility and wavered, that much can be shown.
Thing is, every time I read an e-book claiming that most fathers were universalists I am bound to be disappointed to some degree once I start fact-checking. Don’t get me wrong. I greatly appreciate the books like Dr. Ramelli’s tome you posted a link to in the thread about Athenagoras, but very often universalists just try to prove things that cannot be proven. For example, we can speculate that Chrysostom was secretly a universalist, but we can never make a good case for it to a skeptic. He was a friend of Theodore, sometimes he said things that somewhat imply universalism, and in Homily 9 on Romans he said this: “[T]hey assume punishment to be worse than sin which it is not, but just the contrary. Yet, if it were an evil to the sinner, God would not have added evils to the evil; for He that does everything to extinguish evil, would not have increased it. Being punished then is no evil to the man who has done wrong, but not being punished, when in that plight, is evil, just as for the infirm not to be cured.” This is pretty much all that can be brought forward to support the contention that he was a universalist. Against this, however, we have to put the countless passages where he describes terrifying, infernal tortures and insists that they have no end. The vast majority of his utterances regarding hell can be used to support the eternal torment doctrine. I’d even venture to say that Chrysostom played a major role in solidifying this doctrine in Eastern Christianity and helped to drown out the opinions of Gregory of Nyssa.
A case similar to that of Chrysostom is Hilary of Poitiers. Some universalists make much of the fact that he translated some books of Origen and wrote a couple of things that can be (mis)interpreted to signify universalism, but they ignore passages like this: “[I]f there remains for the saints an expectation, whereas for the wicked there waits the end they have deserved, we cannot conceive that end as a final dissolution (1 Cor 15:24). What punishment would it be for the wicked to be beyond the feeling of avenging torments, because the capability of suffering has been removed by dissolution? The end is, therefore, a culminating and irrevocable condition which awaits us, reserved for the blessed and prepared for the wicked.” (On the Trinity, Book XI, paragraph 28) Consider also these bone-chilling words: “The ungodly have no possible hope of having the image of the happy tree applied to them; the only lot that awaits them is one of wandering and winnowing, crushing, dispersion and unrest; shaken out of the solid framework of their bodily condition, they must be swept away to punishment in dust, a plaything of the wind. They shall not be dissolved into nothing, for punishment must find in them some stuff to work on, but ground into particles, imponderable, unsubstantial, dry, they shall be tossed to and fro, and make sport for the punishment that gives them never rest. Their punishment is recorded by the same Prophet in another place where he says: I will beat them small as the dust before the wind, like the mire of the streets I will destroy them.
Thus as there is an appointed type for happiness, so is there one for punishment. For as it is no hard task for the wind to scatter the dust, and as men who walk through the mud of the streets are hardly aware that they have been treading on it, so it is easy for the punishment of hell to destroy and disperse the ungodly, the logical result of whose sins is to melt them into mud and crush them into dust, reft of all solid substance, for dust and mud they are, and being merely mud and dust are good for nothing else than punishment.” (Homily on the First Psalm, paragraph 19)
My intention in quoting this wasn’t to depress you 
I just wanted to make the point that once we take a comprehensive look at church fathers’ writings instead of just quote-mining them, we might become less confident that the majority of ancient Christians were convinced universalists. But at the end of the day, our goal is not cultivate undue confidence, it is to walk in the Truth through which we must go on our Way to the Life.
