What is meant by "sinless flesh" here? Is it the same as corruptible? And is it to be identified only with the consequences of Adam's sin on the body, or is there more to it than that (e.g. effects on the soul)?
CWR: The Immaculate Conception Revisited by Dr. Leroy Huizenga
The necessity of the Immaculate Conception does not demand an infinite regress of sinless ancestors, nor does the dogma’s necessity involve ecclesiastical voluntarism. Rather, it’s a necessary part of the Catholic conception of the economy of salvation.