R.C. Sproul used to say that in church history, there have been basically only three types of theology: Augustinianism, Pelagianism, and semipelagianism.

To understand what is it stake when identifying these as the only types of theology, we have to go back to the 410s. The issue was Augustine’s teaching of Adam, and Adam’s sin and its connection to us, and the challenge to that teaching by a monk named Pelagius. Pelagius was from the British Isles, but he was rather peripatetic. He made his way to Rome, and then as the Visigoths were making their way to Rome, he went to Africa, and from there he went to the Middle East.

The issue in the 410s was that Pelagius denied the transmission of Adam’s sin. He believed that Adam was an example for us, but that was the extent of the connection. So we’re not born sinners. In fact, we are born with the ability to not sin, and we are born with the ability to choose God and to assert our will to do good and to be good. Augustine attacked this view, and he spent much energy in the 420s refuting Pelagius and some of his key disciples. In 431, at the Council of Ephesus, Pelagius and his teaching and some of those prominent disciples were condemned. But that is not at all the end of the matter.

So what happened next? The issue then was the degree to which Augustine’s refutations of Pelagius would be accepted. In other words, here comes that third type: semipelagianism, a view that carries even to the present day in theology.

When we’re talking about the Semipelagianism view, the issue concerns the full effect of Adam’s sin on humanity. Does Adam leave us sinful? But yet the will is still free to choose, and the will can in fact choose. It can choose to sin or not to sin, and it can choose God or not God. That, in a nutshell, is semipelagianism. Now some folks will say, “Well, that’s semi-Augustinianism, right?” It’s a question of, Is the glass half full, or is the glass half empty? Or you might say, “Have I lost a sock, or have I gained a spare?” Semipelagianism is the halfway position of not accepting what Pelagius was up to, but not wanting to go fully with what Augustine taught.

So we are back to the issue of original sin. When we look this doctrine of original sin, we find it has two dimensions. First it has the fall, that is, Adam’s fall in the garden. In that historical event Adam violated God’s command and plunged himself and all of his posterity into sin. Original sin teaches that all of the sons and all of the daughters of Adam and Eve, all of humanity, are born with an innate moral, corrupt sin nature. They don’t become sinners when they sin; they are sinners. And because they are sinners, they sin. Because we are sinners, we sin.

Augustine further concluded that we are dead in sin, and so God must work in us first in order to save us from our sin. That strikes many as problematic, as if denying moral accountability is denying responsibility. And so theologians introduced this idea that the will is free and we have moral liberty, and we can choose to sin or not to sin. That idea has ricocheted through the centuries of the church. It came up again in the Reformation and in the post-Reformation era.

Those are the three types of theology. Augustinianism, salvation is a work of God alone. Pelagianism, salvation is all about human effort; it’s the assertion of the human will,  and we have the wherewithal to be good and to do good. And in the middle is semipelagianism, salvation is a cooperative work, God and man working together.