Luke was a physician who wrote his Gospel from a medical point of view, naming the diseases of the people that Jesus healed. Luke was associated with Paul. Luke was called the beloved physician. Luke was also what we today would call an investigative journalist. He was not an eyewitnesses of Jesus or these events, but interviewed those who had. He wanted to be sure he got the account as accurate as possible. I read recently that this Gospel may have been written to present as evidence at Paul's trial in Rome. It is addressed to "most noble Theophilis". It's speculated he was a high official in Caesar's court and may have been a new convert. The book of Acts is a sequel to Luke and is a continuation of early church history. Again, it is addressed to Theophilis.
Nicene Christianity became the state church of the Roman Empire with the Edict of Thessalonica in 323 AD, when Emperor Theodosius I made it the Empire's sole authorized religion.
