The burning question in the sixteenth century for the Reformers was “How can I find a gracious God?,” or as Job asks: “...how can a mortal be righteous before God” (Job 9:2; see also Job 25:4). The Church of the Medieval Age had taught for centuries that right standing before God was achieved through the Spirit's inward work of grace in the human heart. More specifically, it taught that men achieve Heaven through the sacrament of baptism that removes original sin and regenerates, then through inner renewal by works of penance that address post-baptismal sins, and then by the grace of sanctification that is never complete in this life, which necessitates that Christians go to purgatory after death to make expiation for their sins. That Church,including the deliverances of Vatican I and II, is still with us today, with no change in its false soteriology  from that time to our own, declaring again as recently as its 1994 Catechism of the Catholic Church that “justification is...the sanctification and renewal of the interior man.” And now an essentially similar soteriology has begun to make its appearance within conservative Protestantism.
To read the entire essay [PDF], click here.
The answer to this question not only divides Protestants and Roman Catholics but it also divides Protestants, as this essay draws to our attention.
A hat tip to Charlie Ray at Reasonable Christian for this article.