St. Irenaeus
St. Irenaeus lived during the second century and was the Bishop of Lyons. St. Irenaeus is known for his theological writings confronting and discrediting Gnosticism, a group of prominent heretical ideas that focused on individual spiritual enlightenment over the teachings of the Church. Irenaeus’ writings were on topics such as redemption through Jesus’ divinity and humanity in response to the Gnostic belief that a secret, mystical knowledge was required for redemption. In addition, Irenaeus’ writings defended the Catholic belief that the body and soul are a composite being, which contradicted the Gnostic teachings that humans are only spiritual beings who separate from their bodies at death. Today, Irenaeus is honored as a Doctor of the Church and one of the most influential theologians in the history of the Church.