Limbo is kind of a strange "no man's land" in which the inhabitants neither are condemned to hell, or at least not to the active suffering of hell (supposedly) nor deemed worthy of heaven. Of course in Scripture all people are under sin's power and are therefore under sin's condemnation (Romans). And all who by faith receive God's gift of grace through his Son Jesus are given eternal life and in Jesus are made worthy in a process that goes on in this life.
Limbo in Dante's The Divine Comedy is the place where people like Socrates and Plato, as well as unbaptized infants exist. They were responsive to light received (infants couldn't respond) but had insufficient light to be among the blessed in purgatory and then in paradise. This is the top wrung, so to speak of Dante's inferno/hell.
Of course I would like to try to tie this in to where we live in the here and now. Not that I buy Dante's picture in its entirety, laden as it is with medieval philosophy and thought, although it surely does have valuable insights for us. I see us either on a downward or upward path. For those who've never heard and theoretically lived in the light of what they had received from God, their place would be limbo in Dante's world. Limbo actually does not seem to be a place of no return for all it inhabitants, in Roman Catholic theology.
But back to my attempted application. This scheme held to by the Church for centuries, but not built well, altogether, from Scripture, is quite interesting as attempting an explanation of the afterlife for all people. One thing we can know for sure, God is good and right in all he does, including his judgment. We have to hold to a kind of "not knowing" about details of this judgment, but that there is a division that will take place between the righteous and the unrighteous.
For us in Christ limbo is not something we go in and out of in our experience. I don't find it helpful that way. We're either on the way of life or the way of death in Scripture. There is no alternative route or road that seems to be in between. This is where Christian theologies can be at logger heads with each other, albeit on minor, but for them vital points. Example is infant baptism which cleanses original sin, though the infant must, down the road repent and believe. Of course many Christians don't hold to this and theology is what it is, the Church's reading of Scripture subject to some changes along the way, as well as some internal differences in many circles of Christianity.
I would venture to say there are times in our lives in which God's patience in grace is active. That can be for those who are not in Christ as well as those who are. Strictly speaking, however, this doesn't fit limbo. This instead is God's active grace at work to draw people to himself and his ongoing work of salvation in his kingdom come in Jesus.
Limbo seems to me to be a human attempt to explain what God has not explained to us. The Church as from Rome would disagree. In the meantime we must not view ourselves or others as in limbo. We're either on a downward turn or an upward climb in God through Christ. Limbo, if true is more in God's territory, who alone knows the hearts of all. Grace is extended to all in Christ; let us be a part of that grace both in receiving it and seeking to help others do the same.
What might you like to add to my stammerings on this subject?