I know that Christs death on the cross reversed Adam’s sin. I guess Christ reversed the spiritual effects of original sin ie. We can get to heaven. But why wasn’t the physical effects of original sin ie. Concupiscence not removed?
First of all, Christ did not exactly reverse Adam’s Original Sin. Adam committed the Original Sin, which shattered humanity’s relationship with Divinity, in real time and space. Once committed, that sin could not be uncommitted.
By His obedience unto death on the cross, Christ offered reparation for Adam’s freely chosen sin of disobedience. We need to keep in mind that all humanity is in Adam as one body of one man.
Baptism erases the contracted state of Original Sin, bringing us back into relationship with God through Sanctifying Grace. Still, the consequences for our human nature, which has been transmitted from our first parent, remain. We are subject to bodily death. And we no longer have
mastery of self which means that we have an inclination to choose sins (triple concupiscence).
Sources: Philippians 2: 7-8; Romans 5: 12-21; 1 Corinthians 15: 21-22;
Catechism of the Catholic Church, Second Edition, paragraphs 397-409; and 377.
Link to Catechism
scborromeo.org/ccc.htm