Iustitia Dei Part 3: Medieval Period

"From its beginning to its end, the medieval period saw justification as involving a real change in the sinner - an understanding which precludes any distinction between iustification and regeneratio. The processus iustificationis includes regeneration or renewal as one of its integral elements, making any such distinction intensely problematic. The notional distinciton that came to emerge in the sixteenth century between iustificatio and regeneratio (or sanctificatio) provides one of the best ways of distingushing between Catholic and Protestant understanding of jusification, making the Reformers' discontinunity with the earlier western theological tradition."

-pg 71-72 Iustiitia Dei by Alister McGrath