Fr. Philip Neri Powell, OP, cites some “givens” from Fr. Frederick Faber for the Catholic teaching of Mary as co-redemptrix. In other words, these are the assumptions. Protestants would, of course, criticize these as unbiblical. We need to recognize that the Catholic teaching does not place Mary in equality with Christ … but it still places her in an improper places. She is a sinner, saved by grace, like us all; the first of the faithful.
1) Our Blessed Lord is the sole Redeemer of the world in the true and proper sense of the word and in this sense no creature whatsoever shares the honour with Him neither can it be said of Him without impiety that He is co redeemer with Mary
2) In a secondary dependent sense and by participation all the elect co operate with our Lord in the redemption of the world
3) In the same sense but in a degree to which no others approach our Blessed Lady co operated with Him in the redemption of the world
4) Besides this and independent of her dolours she co operated in it in a sense and after a manner in which no other creatures did or could
5) Furthermore by her dolours she co operated in the redemption of the world in a separate and peculiar way separate and peculiar not only as regards the co operation of the elect but also as regards her own other co operation independently of the dolours.