Universalism is discussed for a number of reasons, the major ones motivated by the wrong belief that non-Christians are condemned to eternal torment. This has been denied by Orthodoxy but it has caused anguish to some who felt their love ones would suffer for their non-belief.
I think that the criteria for eternal damnation is set by Satan, and thus only those who freely choose to be like Satan are damned, and then only if they are totally aware of what that choice means. Detailed discussion would bring us to some sort of self-annihilation, in that the soul ceases to be in God’s image and becomes a non-soul.