Marcion's teachings departed from traditional Christianity in a number of ways. Most dramatically, perhaps, Marcion rejected the idea that the Old Testament God and the New Testament God were the same being. Up until then, the traditional Church had considered the Old Testament to be sacred and assumed that Christianity was a fulfillment or continuation of Judaism. Marcion's rejection of that idea affected many different doctrines and beliefs.

"Marcion shocked the Church by denying any connection between the Gods of the Old and New Testament. . . . The creator, he argued, was an incompetent being: why else had he afflicted women with the agonies of childbirth? 'God' in the Old Testament was a 'committed barbarian' who favored bandits and such terrorists as Israel's King David. Christ, by contrast, was the new and separate revelation of an altogether higher God. Marcion's teaching was the most extreme statement of the newness of the Christian faith. Combined with virginity and a rejection of marriage, it became 'Marcionism' and continued to attract followers especially in the Syriac-speaking East, far into the Fourth Century." Robin Lane Fox, Pagans and Christians, at 332.

So Marcion taught that the God of the Old Testament was not the God of the New Testament. The God of the Old Testament was the "creating God," but he was harsh, cruel, and incompetent. Marcion contrasted this creating God with the God of Jesus, who was nothing less than love and grace.

www.christianorigins.com/marcion.html

Then we are told that the parents sinned, only after they fell under the influence of the evil one, Satan. So we ask, why would God allow his newly created beings to be in the proximity of this “evil one?” Who created the serpent?

If such a being as Satan was known to exist, why was the angel with the fiery sword meant to protect the garden of Eden not placed there sooner. What good was it to place such an angel of protection at Eden's gates after the damage had been done, and after Adam and Eve had already fallen from paradise?

And how did Satan, if he existed, come to know evil himself. Must not evil have already existed? Certainly, evil must have been in existence, even as a potential, before Satan chose it as a means to and end. Or does this kind of logic not apply to scripture?

Why would God himself know evil, before man was even created, unless God had already brought evil into the world? In Isaiah 45:7, God says "I create evil." In Amos 3:6, Amos is asked "Shall there be evil in a city and the Lord hath not done it." And in Jeremiah 18:11, we read: "I frame evil against you.

(M. Tsarion)