Old Christian heresies never die. Nor do they quite fade away. They linger on in an underground way. They continue to be believed by otherwise good Christians who don’t realize they are holding on to an old heresy.

For instance, when I was in high school, a Catholic high school run by the Christian Brothers, I’m sure some of my teachers were unwitting Monophysites. That is, they believed that Jesus had a divine nature, but they were not at all convinced that he had a human nature. He was God, but he was not man. He was only pretending to be human.

They were also Pelagians. They believed that we could be good if only we tried hard enough. They didn’t honestly believe in the Augustinian idea – the Catholic idea – that we are unable to perform a single good deed without the grace of God.

Of course, that was a long time ago. I was a boy. Now I’m an old man. It’s possible I misremember what my teachers said. If so, I apologize to my old teachers (all of whom, I suppose, are now dead). But that’s how I remember it: some of my old teachers were heretics – material heretics, not formal heretics.

Otherwise, they were fine teachers. The Christian Brothers, I thought, and still think today, were great. I’m sorry to hear that there are so few of them left in the world. My old high school is still a Catholic school, but it no longer has a single Christian Brother on the faculty.

Or take the ancient Manichean heresy, which Saint Augustine was attached to for a number of years. The Manicheans believed that there are two fundamental powers (or gods) locked in an everlasting struggle, a good God (purely spiritual) versus a bad God (purely material). If you were a good person you tried to help the good God, and if you were a bad person you tried to help the bad God. And, of course, you expected that the God of your choice would, in turn, help you.

My guess is that the witches who abounded in the late middle ages were latter-day Manicheans who had decided to serve on the side of the bad God, hoping that their God (the Devil) would help them in their many earthly concerns. Of course, they didn’t realize they were de facto Manicheans. How could they, being poor and uneducated? Jesus, as they saw things, was on the side of respectable people. So they had little choice but to turn to the Devil.

Today, in the Catholic world (or at least in the American Catholic world), the old heresy that flourishes underground and unwittingly is that of Marcion. He was born in the Greek city of Sinope (in Asia Minor, on the Black Sea) about AD 85 and died about AD 160 in Rome, where he had been excommunicated from the Church.

Marcion taught that the God of the Old Testament and the God of the New Testament were two quite different Gods. The God of the OT wasn’t exactly an evil God. Instead, he was a God of justice, and therefore it was his duty to punish the many sins of humanity with the pain and suffering we deserve. This was the God of the Jews. He was a material God. It was this OT God who created the world, this world of sin and misery.

In the Marcionite view, the God of the NT, by contrast, is a God of mercy. In keeping with his loving, merciful nature, this higher and better God does not punish sin. He forgives sin. He is the father of Jesus Christ. He is a purely spiritual (nonmaterial) being. And so is Jesus, who only appears to have a human body. This NT God saves us from the miseries of this lower world; he brings us to heaven.

Marcion denied that there is any continuity between Christianity and the religion of the Jews. He rejected the Old Testament, for he thought it a book about the inferior, material God of justice. He even rejected portions of the New Testament. He accepted (with a few redactions) the Gospel of Luke and ten of the Pauline epistles. Everything else, bearing traces of the Jewish OT God, he tossed out.

I’m not saying that there are Catholics today who embrace the whole of Marcion’s theology. No, but there are many who embrace his central point, namely that the true God is a God of pure mercy, not a God of justice. The true God forgives sins, he doesn’t punish them.

It’s not only Catholics who embrace this heresy. Modern persons generally embrace it. Those of us with a modern mind find it hard to bear the thought that anybody goes to Hell. Well, maybe Hitler and Stalin. And even they should not be kept there for eternity. After – say – ten thousand years, they should be set free.

And among Catholics, it is not only rank-and-file Catholics who think God is a God of mercy-but-not-justice. A few years back Pope Francis established a Year of Mercy. Will he soon declare a Year of Justice – a year in which to remind ourselves of the ancient teaching of the Church and the Bible, that the God of Christianity is a God who punishes sin?

Pope Francis, as he demonstrated in Amoris Laetitia, wants mercy to be shown to divorced-and-remarried Catholics. And as he demonstrated in his recent amendment to the Catechism of the Catholic Church, he wants mercy to be shown to those who commit horrible murders.

And as he demonstrated in his revocation of the restrictions imposed by Pope Benedict on Cardinal McCarrick, he wants mercy to be shown to homosexual prelates who have inflicted immeasurable harm on the Church.

Old heresies, as I say, never quite die.

*Image: The Triumph of St. Thomas Aquinas Over the Heretics by Filippino Lippi, 1490 [Santa Maria sopra Minerva, Rome]. Lippi’s (and assistant Raffaellino del Garbo’s) fresco depicts St. Thomas surrounded by Philosophy, Astronomy, Theology, and Grammar. At the sides and in the foreground are various defeated heretics.