> "[The Marcionites] were perhaps the most dangerous foe Christianity has ever known"
Catholic encyclopedia on "Marcionites": https://www.newadvent.org/cathen/09645c.htm
Stumbled upon this from people posting about other heresies and was thinking more reading about heresies might be helpful for people to understand and avoid error
if this is your motivation, users like crusaderpepe are frequently posting against "Jewish errors" from a Catholic perspective; hence you could be Catholic and oppose certain Jewish errors
> The Catholic Encyclopedia only gives the Catholic perspective.
Naturally, although I can see why people might independently side with Catholicism, as Marcionism proposes:
Two different gods (one of Old Testament, one of New); the teaching Jesus only appeared to be human (docetism); matter is inherently evil contrary to Genesis 1:31 that all that God made was "good" (like Manicheanism); Gnostic tendencies of salvation through secret knowledge, rather than through faith and works.