Actually Marcionism was a 2nd century heresy, not a 1st. There are actually few known 1st century heresies, and what there are, are poorly documented. The most important would have been "the Judaizers," whom Paul addressed in Galatians, and the Ebionites/Nazarenes.
It's no coincidence that both of these heresies considered Christ's mission to have been primarily or solely to Jews, and not Gentiles. |