Final answer:
The author of 'On the Misery of the Human Condition' is not specified in the information provided, but St. Augustine is a prominent figure whose thoughts on human nature were influential in shaping Catholic Church doctrine.
Step-by-step explanation:
The author of On the Misery of the Human Condition, whose message was adopted as official doctrine of the Western Catholic Church, is not explicitly mentioned in the provided information. However, based on the context of late medieval Christian philosophy and its focus on human suffering, one of the key figures whose writings on the human condition were influential was St. Augustine. His works, particularly the Confessions, focused on his struggles with faith and sin, with underlying themes that human nature is flawed due to original sin. Augustine's views on human nature and suffering were deeply interwoven with the doctrines of the Catholic Church during late antiquity and throughout the Middle Ages. While Joseph de Maistre also expressed ideas about the depravity of human nature, his writings are from the early nineteenth century and not directly associated with the text in question.