The “heretic” Marcion is a significant figure in the history of early Christianity but the sources for our dates for his activity are contradictory. It is quite possible that if we attempt to understand the reasons for these contradictions in the sources we will see that Marcion’s influence on our canonical New Testament texts as far more influential than it is generally portrayed today in histories of early Christianity. (For more background on Marcion see the Center for Marcionite Research and at Early Christian Writings.)
One recent fresh look at the date — and influence on the New Testament writings — of Marcion is found in Tyson‘s Marcion and Luke-Acts. (See the tag tyson-marcion-luke-acts/). Tyson argues that Acts was composed in the second century as a response to Marcionite Christianity, which was possibly the largest brand of Christianity at the time and which claimed Paul as its sole apostle.
The ideological bias for dating Marcion late
Part of Tyson’s argument is the possibility that Marcion himself began his work considerably earlier than is often assumed. The generally accepted dates for Marcion are based on a face-value reading of Church Fathers’ polemics against his doctrines. Tyson and others remind us that these authors had an ideological reason for placing Marcion as late as possible: their theological constructs dictated that Christianity heresy infected Christianity late, sometimes as late as 117 c.e. (the accession of emperor Hadrian). The idea was to keep false teaching far removed from what they believed was the “original purity” of the Church and the time of the twelve apostles.
Hoffman’s reasons for dating Marcion earlier
Tyson draws in part on R. Joseph Hoffmann’s argument in his discussion of the possibility of a much earlier date for Marcion.
Following is a dot-point outline from R. Joseph Hoffman’s Marcion, on the restitution of Christianity. It’s all from Hoffmann’s second chapter and my numbering matches the original chapter sections.