Irenaeus of Lyons, Against Heresies 4.33

The spiritual disciple is the one who truly receives the Spirit of God. This Spirit was present from the beginning in all God's arrangements with humanity; he announced future events, revealed present realities, and explained the past. He judges all things, yet is himself judged by no one. For he judges the nations—creatures who serve the created order rather than the Creator (Rom 1:25), consuming their entire effort in vain with depraved minds. He also judges the Jews, who failed to perceive the word of liberty and refused to go out free, even though their Liberator was present with them. Instead, they pretended to serve God outside the Law at the wrong time, acting as if He needed nothing, and they refused to know or understand the advent of Christ, which He accomplished for human salvation. All the prophets foretold two advents of His. The first: He became man and knew weakness; He rode on a donkey's colt; He was the stone rejected by the builders; He was led like a sheep to the slaughter; by the stretching out of His hands He overthrew Amalek; He gathered the scattered children from the ends of the earth into the Father's fold; He remembered His own dead who had fallen asleep and descended to them to bring them up. The second: He will come on the clouds, bringing a day that burns like a furnace; He will strike the earth with the word of His mouth and slay the wicked with the breath of His lips; He will hold a winnowing fork in His hand, clear His threshing floor, gather the wheat into His barn, and burn the chaff with unquenchable fire (Isa 11:4; Matt 3:12; 2 Thess 2:8; Mal 4:1).

Now let us examine the teaching of Marcion: how does he accept that there are two gods, separated by infinite distance? How can the one he calls 'good' be good, when he lures away strangers from the God who made them and summons them into his own kingdom? Why does his goodness fail by not saving everyone? Why does he appear good toward human beings, yet prove most unjust toward the One who made them, by stripping that Maker of what belongs to Him? How can the Lord be just if He springs from another Father, yet assumes this human condition, declaring the bread to be His body and the cup's mixture to be His blood? Why did He confess Himself to be the Son of Man if He did not undergo the generation that comes from man? How could He forgive us the sins we owe to our Maker and God? How could He be crucified when He was not flesh, but was born only in appearance as a man—and from His pierced side blood and water flowed out? What was that body the buriers buried? And what was it that rose from the dead?