I found the following on the net which would explain it but I don’t know if it is accurate and true of course as it’s not from the Bible:
In the 4th.Century AD, the Roman Emperor Constantine converted to Christianity. He convoked the Council of Nicea in 325 AD. This Council determined that God was a Trinity. All who did not believe this were called heretics. Thus, there was created a sharp division between those who held to apostolic beliefs, and those of the militant camp of Constantine. This division has lasted right through to the present day. Through Constantine, Imperial Rome was transformed to Ecclesiastical Rome (the Catholic Church). In the eleventh century AD, the Catholic Church broke into two parts: Roman Catholic; and Eastern Orthodox. These two sections are represented by the two iron legs of Daniel’s image. The feet are a mixture of iron and clay. Clay is symbolic of humanity, and here represents nations. Different toes, represent different nations. But, these nations are partly iron. That means, this collection of nations is influenced by ecclesiastical Rome. In the end times, this group of nations will form Catholic Europe. It will be hostile towards Jesus and try to destroy Him. But, Jesus (the stone) will destroy them at the battle of Armageddon. In doing so, all nations will become subject to the Lord, who will grow together with His saints, to fill the whole earth. Then, the peaceful Kingdom period will begin.
Revelation 12 and 13
Without going into much detail, these two chapters deal with the rise of the apostate church that would oppose the Truth and its believers. The apostate church was able to operate with the blessing of the Emperor Constantine (12:5) who embraced Christianity for his own political ends. Thus, Imperial Rome became the state sponsor of the so-called Christian church. He endorsed the Council of Nicaea’s declaration of the doctrine of the Trinity (AD 325), and commanded that it must be believed by all Christians. Those who did not were deemed heretics and subject to abuse. This abuse continued for many centuries resulting in horrible conditions and death for true believers. The ;papacy is characterised by the beast of 13:2. This is the same beast of Dan 7:4-7. The Lord Jesus will finally destroy this false system of worship when He returns (14:8;18:2,21).