Justin Martyr clearly had no doubt about the resemblance of the Mithraic to the Christian ceremony.
"Pagan & Christian Creeds" by Edward Carpenter
It is impossible to admit an imitation of the Mithraic mysteries then, because at that period they had no importance whatever.
"The Oriental Religions in Roman Paganism" by Franz Cumont
In old Pagan and Mithraic times we know that the sacrifice of the ox was common.
"Archaeological Essays, Vol. 1" by James Y. Simpson
Even in the sacramental meals of later times, Eleusinian, Christian, and Mithraic, there is no trace of the theory under consideration.
"Introduction to the History of Religions" by Crawford Howell Toy
But the symbolism is also largely associated with Mithraic worship.
"Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 5" by Various
The Eucharist itself was probably Paul's own adaptation of a Mithraic rite to Christian purposes.
"Solomon and Solomonic Literature" by Moncure Daniel Conway