A strong case against a proto-Luke edited by Marcion and later by Luke

[Giuseppe]

1) the birth narrative of canonical Luke is recognized as anti-marcionite even by who thinks that proto-Luke preceded Marcion.

2) Marcion is contemporary of Justin

3) Justin appears to know Luke’s birth narrative with his mentions of Jesus’ circumcision and reference to a manger

4) therefore: proto-Luke concides strictly with the Gospel of Marcion and it didn't exist before Marcion

CONCLUSION: if you think that the birth narrative is anti-marcionite per se, then you are obliged - obliged! I say - to assume that proto-Luke == Mcn.

[Giuseppe]

Clearly the hypothesis (2): Marcion is contemporary of Justin

is the weakest premise in the proof.