At which council was the concept of original sin defined?

The concept of original sin was formally discussed and defined at the Council of Carthage in 418 AD. This council addressed the theological implications of original sin, particularly in the context of human nature derived from the Fall of Adam and Eve. It affirmed that all humans inherit a fallen nature and are therefore subject to original sin, which is a fundamental element of Catholic doctrine. This understanding has had a profound impact on Christian theology, influencing views on baptism and redemption.

While other councils, such as the Council of Trent and the First Council of Nicaea, dealt with various theological issues, they did not specifically define the concept of original sin. The Second Council of Constantinople focused on Christological disputes and the nature of Christ rather than the doctrine of original sin. Thus, the Council of Carthage holds historical significance as the location where this crucial concept was articulated.