This possibility is more concrete than one may imagine:
A general hypothesis suggests itself. We are told concerning Marcion that towards the end of his life he sought to be received back into the Church, and was prepared to invite his followers to return with him, but was prevented by death. Our Mark, then, might be his gospel, with the preliminary addition of the first twenty verses, and other changes. According to Tertullian, his gospel began with an account of the coming of Jesus to Capernaum, and being hailed in the synagogue as the Holy One of God. Marcion may have prefixed the preceding matter by way of partial accommodation ; or one of his sect may have done it. An orthodox hand would hardly have been content with so little.
(J.M. Robertson, Jesus and Judas, p. 229-230, my bold)
Who is repeating Tertllianus' inventing of lies about Marcion? He had already invented enough of them!
Who does not understand that? Mr.Robertson? How dumb is he?
Marcion explicitly did NOT come from the church, so he also did not want to get back. He had only visited them ONCE. Their only scripture was the OT and they probably had never heard of what Marcion was saying. He was declared a heretic, but of the OLD testament. Marcion was the first person with a NEW testament, not them. Tertullianus is lying of course, blackening Marcion as been told by Irenaeus.
Why don't you read about this on the Wikipedia and others? It is all there!!
