Do you have a better site? As I said, I found very little on the Ulansey site to confirm, and several things that contradicted the athiest site which had Mithra as another version of Jesus.
like the other ancient "mystery religions," such as the Eleusinian mysteries and the mysteries of Isis, Mithraism maintained strict secrecy about its teachings and practices, revealing them only to initiates. As a result, reconstructing the beliefs of the Mithraic devotees has posed an enormously intriguing challenge to scholarly ingenuity. . . .
Owing to the cult's secrecy, we possess almost no literary evidence about the beliefs of Mithraism. The few texts that do refer to the cult come not from Mithraic devotees themselves, but rather from outsiders such as early Church fathers, who mentioned Mithraism in order to attack it, and Platonic philosophers, who attempted to find support in Mithraic symbolism for their own philosophical ideas. However, although our literary sources for Mithraism are extremely sparse,
What the athiests are spreading about Mithraism is a lot of bull fertilizer based on what Mr. Ulansey concedes is "extremely sparse" evidence. Mr. Ulansey himself seems to be rather eccentric and quite an enthusist for leftist causes and, for want of a better description, new age spirituality.