The mysteries declined quickly when the emperor Constantine raised Christianity to the status of the state religion. After a short period of toleration, the pagan religions were prohibited. The property of the pagan gods was confiscated, and the temples were destroyed. The metal from which Constantine's gold pieces were coined was taken from the pagan temple treasuries.
The main pagan "strong holds" were Rome and Alexandria. In Rome, the old aristocracy clung to the mysteries and in Alexandria the pagan Neoplatonist philosophers expounded the mystery doctrines. In 394, the opposition of the Roman aristocracy was crushed in the battle at the Frigidus River (modern stream of Vipacco, Italy and stream of Vipava, Yugoslavia).
According to the Christian theologian Origen, Christianity's development during the time of the Roman Empire was part of the divine plan. The whole Mediterranean world was united by the Romans, and the conditions for missionary work were more favorable than ever before. He explains the similarities as natural considering the cultures etc. The mystery religions and Christianity had many features in common. Some examples of this are found in their time of preparation prior to initiation, and periods of fasting. Their were pilgrimages, and new names for the new brethren. Few of the early Christian "congregations" would be called orthodox according to later more modern standards.
Though for many years, the pagan "churches" of this area tried to bring about a unity among their "doctrines", beliefs, and practices to raise support for their practices, the Christian philosophies and doctrines were so organized and strong that this fell as well. Little did they know that a couple hundred miles away, peoples were still worshipping in pagan temples.
Let's take a look up north.
The worship of trees goes far back into the history of man. It was not until Christianity converted the Lithuanians toward the close of the 14th century that tree worship was thought to be in the past. The truth is...whereas they are not worshiped, they are still honored by society today in the burning of the Yule log, May Day bon-fires, Kissing under the Mistletoe, and the ever famous Christmas tree.
The worship of the oak tree or god appears to have been universal by all branches of the Aryan stock in Europe. Both Greeks and Italians associated the tree with their highest god, Zeus or Jupiter, the divinity of the sky, the rain, and the thunder. Possibly one of the oldest and most famous sanctuaries in Greece was that of Dodona, where Zeus was revered in th oracular oak. The thunderstorms which are said to rage at Dodona more frequently than anywhere else in Europe, would render the spot a fitting home for the god whose voice was heard alike in the rustling of the oak leaves and in the crash of thunder.
Zeus of Greece, and Jupiter of Italy both were gods of thunder and rain, and to both the oak tree were sacred.
To the Celts, or Druids, their worship was conducted in oak groves. The Celtic conquerors, who settled in Asia in the third century b.c., appear to have carried with them the worship of the oak to their new home. In the heart of Asia Minor, the Galatian senate met in a place which bore the Celtic name of Drynemetum, "the sacred oak grove" or "the temple of the oak."
In Germany, we find that the veneration for sacred groves seems to have held the foremost place. According to Grimm, the chief of their holy trees was the oak. Again, here we find that it is dedicated to the god of thunder, Donar or Thunar, the equivalent of the Norse Thor. Among the Slavs, the oak tree was sacred to the thunder god Perun. Among the Lithuanians, the oak tree was sacred to Perkunas or Perkuns, the god of thunder and rain.
The Christmas tree, usually a balsam or douglas fir, was decorated with lights and ornaments as a part of Christmas festivities. The use of evergreen trees, wreaths, and garlands as a symbol of eternal life was an old custom of the Egyptians,
Chinese, and Hebrews. Tree worship, common among the pagan Europeans, survived after their conversion to Christianity in the Scandinavian customs of decorating the house and barn with evergreens at the New Year to scare away the devil and of setting up a tree for the birds during Christmastime. It survived in the custom observed in Germany, of placing a Yule tree inside the house in the midwinter holidays.
The modern Christmas tree originated in Western Germany. The main prop of a popular medieval play about Adam and Eve was a fir tree hung with apples (the tree of Paradise) representing the Garden of Eden. The Germans set up the Paradise tree in their homes on December 24, the religious feast day of Adam and Eve. They hung wafers on it (symbolizing the host, the Christian sigh of redemption). In later tradition, the wafers were replaced by cookies of various shapes. Candles were often added as the symbol of Christ, though they were also a pagan symbol for the light of the God.
As we can see, even though the pagan community has been trod upon, it was never destroyed. The date of Christmas was purposely fixed on December 25 to push into the background the great festival of the sun god, and the Epiphany on January 5 to supplant an Egyptian festival of the same day and the Easter ceremonies were set to rival the pagan spring festival.
Let's take a look at a few of the holidays and compare.