When we explore the religious practices of the ancient Greco-Roman world we see that they did not practice different religions, but they practiced many different versions of the same religion. Basically honoring various gods with temples, rites, and various rituals, and tributes, which is referred to as polytheism. They had many gods and many temples. Each god had unique attributes and had control over certain aspects of life, and the world. Each one would be sought at different times depending on the circumstances of the individual seeking help from the gods, or wanting to honor, or worship a god for a specific perceived blessing that was received.
It has been recorded in the history books that Emperor Constantine converted to Christianity in the fourth century AD. This is a misrepresentation of what actually took place and what the Emperor was endeavoring to accomplish. He did not convert to Christianity. What he actually did was he converted Christianity, and adopted the Christian God to the religion of the Empire.
He did not remove all the other gods from the Roman religious repertoire, he merely added another god to the list of very important gods in the Roman religious experience. We see many pagan aspects of this fact when we examine the main religion that eventually emerged from Constantine's corruption of the truth. The Roman Catholic Church developed as a result of many pagan practices mixed into the corrupt "Christian" framework that Constantine fabricated. It was some years after Constantine that the pure pagan polytheistic practices were removed comletely, and the Roman Catholic Church became the dominant religious influence in Europe.