Christ, I can't believe I've nothing better to do than this.
The doctrine of the Immaculate Conception of Mary and the Assumption of Mary used to be theological opinions that were generally accepted long before they were infallibly proclaimed as dogma, so I and many Catholic believe that Limbo is the destination for the souls of unbaptized infants. But some other Catholics think that they go to heaven. Either way, the sins that cause damnation are mortal sins so infants and young children are too young to be able to commit those kinds of sins.
The doctrine of the Immaculate Conception has a claim of being part of the deposit of faith prior to the dogmatic statement within
Ineffabilis Deus because Christians believed it during the early centuries of the faith. There are strong arguments against it being a dogma such as the Orthodox claim, but for the sake of brevity, I'll assume it's correct.
The doctrine of Limbo is contrary to earlier statements within the Church such as the writings of Saint Cyprian of Carthage who state otherwise. Several popes, perhaps most famously within
Unam Sanctam but also repeated by the Council of Florence state strongly otherwise.
Feenyism is condemned, that an unbaptised martyr cannot know God. But the Church cannot state definitively that Infants who die before baptism (including miscarriages who in Catholic thought do have souls) are saved.
If anything, infant damnation is historically the more popular opinion. You've only to crack open something like Dante's
Inferno and note that the first circle of hell is specifically for "Virtuous Pagans and unbaptized Infants". It's not a nice place, but I suppose they're only suffering a little rather than being boiled upside down in a barrel.
They were originally pagan conquerors but they were made valid when they converted to Christianity and were recognized by the Byzantine Emperors and Popes. The Byzantine Emperors as successors to the Roman Emperors had the authority to recognize them as valid.
The Byzantine Emperor's were not Catholic, all of them practised Caesaropapism. You're relying upon an authority that humiliated several popes and tortured one to death for legitimacy in the Catholic faith. This is a bit of a stretch.
Interestingly, the Byzantine Emperor's never accepted the Western Rulers as true Kings. They acknowledged them as warlords, but only addressed themselves with royal titles because they believed they had the rightful claim to the west. Irene got the closest when she briefly toyed with the idea of marriage to Charlemagne, but she ultimately turned from it because "He was a pretender".
According to the Byzantine Emperor Irene (Female Emperors always used male titles), the Holy Roman Emperor (Charlemagne) was an illegitimate ruler.
Making it so that it would not happen would be interfering with the free will of his creation. Satan chose to rebel against God, inventing sin and then Adam and Eve chose to eat the forbidden fruit. It was the choices of Satan, Adam, and Eve that made the world the way it is today.
Presuming your father murdered someone, would it be just if the state executed you for his crime?
According to Yahweh's logic, massacring all his descendants is perfectly just.
No, Yahweh created Satan, knowing he would rebel and giving him the resources to do so. He could also have stopped Satan at any time, knowing his creation who hadn't obtained knowledge of Good or Evil would do as he suggests.
Divine Command theory is more compelling on this front, but it does make Justice and morality purely whimsical.
As I said, while those religions were older, they were from BEFORE England was established as a nation in 927 AD. Catholicism is not the traditional religion of the region of England but it is the traditional religion of the nation of England.
Either way, Protestantism has been the State Religion of England for far longer than Catholicism was at this point. Even the Church of England has a better claim to authority by age than the Catholic Church.