So kiddo, a long, long time ago, people believed in lots of different gods and goddesses. But then, a man named Jesus came along and taught people about loving one another and being kind. He became really popular and lots of people started following him.
After Jesus died, his followers wanted to spread his teachings and they started telling stories about him and writing them down. These stories became the Bible. The first part of the Bible is the Old Testament and talks about the history of the Jewish people, and the second part is the New Testament and talks about Jesus and his teachings.
As time went on, more and more people started following Jesus and his teachings. But there were also lots of disagreements about what his teachings meant and how people should follow them.
Eventually, the Roman Empire became Christian and made it the official religion. This led to more disagreements and different groups of Christians formed. Some groups believed one thing, while others believed something different.
One of the big debates was about the nature of Jesus. Some people believed that he was fully human and fully divine, while others believed that he was only divine or only human. This led to an important meeting called the Council of Nicaea, where church leaders came together to discuss these issues and come to an agreement.
As time went on, the Christian church became more powerful and influential. But there were still disagreements and debates about how to follow Jesus' teachings. Different groups formed, such as the Eastern Orthodox church and the Roman Catholic church.
So, in short, the late ancient history of Christianity is a time when people were figuring out what it meant to be a follower of Jesus and how to best follow his teachings. There were disagreements and debates, but ultimately the Christian church became a very important part of the world's history.