Limbo was never a doctrinal teaching. It was a theory–a lot like the theory of, say, the sun revolving around the earth. From the perspective of most people throughout history until fairly recent times (and I say this because the theory that the earth revolved around the sun, not vice versa, existed among individuals before Copernicus et.al), who looked up in the morning and saw the sun APPEAR to move across the sky, it seemed quite obviously that it anything was moving, it was the sun, not the earth.
We know differently now, and so that theory has been pretty well disproven.
Still, the basic truths that there exists a sun, a moon, time, days and nights etc., remain. The basics have not changed.
Same with Limbo. The theory was that since Baptism is the nominative or normal method of salvation, and that all humanity save Adam and Eve, Mary, and Jesus have been afflicted with original sin, that if an infant dies before Baptism, in original sin, he/she could not enter heaven, at least in the normative way. But the infants had not committed personal sin. A theory developed that God (who is all merciful) might have a place of ‘natural happiness’ set aside for such infants.
But this was only a theory, like the geocentric theory of old.
We do know that Baptism is the normative way for salvation. That is basic; it doesn’t change. We also know that God is all-merciful. That hasn’t changed.
But people were misunderstanding the Church’s teaching. With the doctrine of Limbo seeming to many to be ‘dogmatic teaching’, and with the rise of abortion rates, many were questioning whether the sin of abortion was ‘mitigated’ in a sense because God had ‘planned out’ Limbo. Others were questioning the ‘fairness’ of God in punishing (in their mind) the infants while over the last 35 years more and more parents were engaging in the sin of aborting their children, with no divine punishment and more and more people attempting to argue that abortion was a GOOD thing.
And so the Church (which had been considering this matter, as indeed it does to all that goes on within the Church) prayed and pondered, and our Holy Father has recently spoken out trying to make things more clear. . .that Limbo never was ‘dogma or doctrine’, and that we need to trust these infants to God.
The basics haven’t changed. Limbo as a theory was ‘trusting the infants to God’ in that it hoped that God would not send the infants to hell.
That hasn’t changed. We still trust that God will not send these innocents to hell for their lack of baptism is not their choice. We actually see that God is not limited to a ‘limbo’ but can have a wider–an infinite–field for His mercy. So we trust those innocent little children TO his mercy.
