I get the picture that Roman religion had been dominated by
Mithraism peaking towards the end of the second century and as it declined,
Jesus- Christianity amongst many others, was replacing it. If we had been able
to take a sociological survey at that time, namely finding out what people were
actually doing as opposed to being bamboozled by the entirely biased Bible
writings, we would probably find that Mithraic practice was the norm and was
the source ritual for the ‘Christian’ last supper (remember the Saviour Mithra
or Mithras was a christ too). The specific parallels can be explained by the
later Roman Church under Constantine taking this prevailing pre-Jesus, Mithraic
‘eucharist’ symbolism of bread and wine into the syncretised Catholic worship.
Mithra was called both the ‘Lamb of God’ and the ‘Good Shepherd’ and is
depicted standing above a cross.
Since the Vatican was built on top of the Roman Mithreum (underground
church) its continuity with that cult is palpable. There exists in the caverns
there the Mithraic inscription “Whoever does not drink of my blood and eat of
my body, the same will not be with me in paradise”.
So indeed eating the lamb would seem superfluous and innovative, best stick with tradition. The Jewish converts by now in the fourth century (when the Bible books were selected and edited) having been thoroughly Romanised.