Could the Marcionites have it right and many are worshoping the wrong God today?

Marcionites founded in A.D. 144 in Rome by Marcion and continuing in the West for 300 years, but in the East some centuries longer, especially outside the Byzantine Empire. They rejected the writings of the Old Testament and taught that Christ was the Son of the good God and not the Son of the God of the Jews, but one who was different from the God of the Ancient Covenant.