I am not familiar with the Methodist Theory of Salvation, but the term “Original Sin” is more in tune with Catholic Theology.
Protestants of the Calvinist tradition call the concept of the inherited sin of Adam “Total Depravity”, and Less TULIP-y Evangelicals call it the “Sin Nature”. All three of these concepts assume the need for Salvation, either by Infant baptism or a profession of Faith (Conversion, being Born Again, or getting “Saved”).
In NONE of these faith traditions is the pre-born infant considered worthy of murder because he or she is still in “Original Sin”.
To deny a baby the opportunity to become a Child of God by snuffing her out in the womb, and then using “Original Sin” as the excuse, is mind-bogglingly EVIL.
Needless to say, we Catholics join you and other good Protestants in determined opposition to the notion that original sin justifies the killing of the innocent unborn. God bless you and yours!