When a new way of thought or a new creed is introduced to a nation they often try to find similarities between the new idea and existing ones.
It makes the new way of life easily acceptable for people without feeling that something has been imposed on them.
However, many other scholars claim that liturgical and doctrinal resemblances between Christianity and Mithraism prompted Christians to attack the old creed.

Ruins of a European Mithraeum
The followers of Mithra worshiped in temples called Mithraeum which served as a meeting place. Partly underground, it was often a replica of the cave in which Mithra was said to have caught and killed a mystic bull in.
While Mithraism was the official religion of the old world why is there no evidence of Mithraic monuments or Mithraea ruins anywhere?
Excavations have revealed a Mithraeum under most old churches in Iran and Europe.
Throughout the Roman Empire and under the attack of the Christians, numerous Mithraea were abandoned, destroyed, or transformed and incorporated into Christian churches.
In Iran, the Parthian Mithraeums were first turned into Sassanid fire-temples and after the advent of Islam into mosques.
Archeological studies in Iran have revealed the remains of pre-Islamic monuments believed to have been of Mithraic nature under many of the country's mosques.