To set the scenery: No New Testament nor any Patristic scholar, so far, has come up with the idea that Marcion himself wrote a Gospel, hence, even less has anybody advanced the suggestion that he had written The Gospel, or, more daringly even, that Marcion produced the first work of this genre, although scholars have granted that he was the one who created the titles ‘New Testament’ (W. Kinzig) and also the first to apply the term ‘Gospel’ to a written account (H. Koester).
Now it is neither an abduction by aliens nor a longing for alien ideas, but simply the result of reading sources, and especially Tertullian’s Adversus Marcionem, that I have come across a few good arguments that make a case for all three suggestions, namely that:
1) Marcion was the author, rather than a redactor of a Gospel
2) He had written The Gospel and
3) He was the innovator who created the first work of this new literary genre from whom all other Gospels depend.
(more in the workshop on Marcion and the Gospels)