EDITOR’S NOTE:  Below, Gregg R. Allison, professor of Christian theology, discusses his new book, The Unfinished Reformation: What Unites and Divides Catholics and Protestants After 500 Years, with Towers editor S. Craig Sanders.

CS: Your co-author, Chris Castaldo, was raised Roman Catholic prior to his conversion and you have ministered in Catholic contexts. How did this book come together with the two of you working on this project?

GA: The origin of the book was Anthony Lane, supervisor for Castaldo’s Ph.D., asked Chris  if there is a resource that deals with Catholicism and Protestantism, showing the commonalities and the differences, and Chris couldn’t think of any. He contacted me and asked if I was aware of any of those kind of resources and my response was, “No, but why don’t you and I write it?” So, that was the germ of the idea and now we’ve got the fully flowering plant.

CS: As we’re approaching the 500th anniversary of the Reformation in 2017, what remains unfinished?

GA: There are still significant divergences — in our book, we list 16 of them — that continue to divide Protestantism and Catholicism. If we could boil them down to two major categories, one is authority and the other is salvation, which reflect the two principles of Protestantism: Sola Scriptura, the assured authority, and salvation which is justification by God’s grace by faith in Christ alone. So very briefly we would maintain that what remains unfinished are these two points: Authority, what is the authority, who or what is the authority in our church, and then how does one become right before God.

CS: Evangelicals and Catholics Together commemorated its 20th anniversary and evangelical attitudes toward Catholics have changed with Pope Francis. What are the benefits and dangers of some of these ecumenical efforts?

GA: A danger would be to overlook or minimize these standing differences and move toward a mere Christianity that is a lowest-common-denominator approach, ignoring or just refusing to deal with the differences. That I think is the major danger, which is going to be reflected this October when Pope Francis goes to Lund, Sweden, to participate in Reformation events where it is believed he will claim that the Reformation is over. I think that’s not a true statement, it’s not a helpful statement, it’s not a fair statement. The advantages are that we can focus on the genuine commonalities that unite us and these are the doctrines of the Trinity and the person of Christ and things like that. In dialogue we can learn more about one another’s perspective, appreciate these points of commonality, and not fight against or kill one another as was being done in the 16th century. And also talk very honestly and openly about the differences that remain and see if there could be movement from the two traditions.

CS: We’ve had some controversy recently in regard to the Trinity even in our own Reformed evangelical circles. What can we learn by the Catholic confessions of faith and their view of the doctrine of the Trinity?

GA: That the Catholic confession of the doctrine of the Trinity is the traditional Protestant confession of the doctrine of the Trinity because we inherited that from when the church was united in the early church. So that’s the Catholic doctrine and that’s our doctrine. That’s our legacy and our heritage just as much as it is for the Catholic Church. And I would argue that theological consensus on the doctrine of the Trinity enjoys presumptive authority in our theological discussion and formulations on the doctrines of the Trinity. It is truth until proven otherwise and while that’s not ultimate authority — that comes from Scripture only — it has presumptive authority in terms of it representing the consensus of the church; it’s a beautiful summary of biblical teaching and it is what the church is bound to believe.

CS: You note the need for co-belligerence, referring to what Francis Schaeffer taught about forming alliances in the public square. What are ways we can do that with Roman Catholics?

GA: On any social and moral issue that we agree with Catholics and Orthodox, Mormons, Jehovah’s Witnesses, Muslims, Buddhists, Hindus, agnostics, and atheists. On these moral and social issues where there is agreement in favor of a culture of life over a culture of death, I would be very much in favor of co-belligerent activities. So, protesting against abortion, trying to pass legislation against stem cell research and genetic engineering and things like that, advocating for good education available for all people, always advocating for biblical human rights; we can do that regardless of our religious persuasion.

CS: When you talk about the issues of authority and salvation, the Catholic view of the church is intertwined with both of those categories. In what specific ways does a Catholic view of the church differ from a Protestant understanding of the church?

GA: The Catholic Church claims to be the one true church of Jesus Christ. That one true church of Jesus Christ subsists only in the Catholic Church and believes it is the ongoing incarnation of Jesus Christ.  It is Christ in his divine nature, his human nature with his body the church — the totus Christus — that is the Catholic Church. So it of course possesses ultimate authority. The magisterium, the teaching office of the Catholic Church, interprets Scripture, promotes tradition, guides the church, and the church is also the means through which anyone and everyone must be saved. It is through the church, particularly through its sacraments, that grace is communicated to people, to non-believers to bring them into faith in Christ, to the Catholic faith to nourish them, and so the church is essential both in terms of authority and of course salvation.

CS: In your book, you mention that Mary is one of the greatest stumbling blocks toward any type of unity between evangelicals and Catholics. It seems that a lot of Protestants often have a misunderstanding of what Mary’s role is in the church. How does her role factor into these categories of authority and salvation?

GA: According to Catholic theology, Mary was predestined by God to become the mother of the incarnate Son of God. In order for her to become the mother of Jesus Christ, she had to give her willing consent to God’s will. Therefore she had to be prepared, she had to be in a state in which she would indeed say yes to God’s will. So the Catholic Church believes she was conceived without sin. This is the Immaculate Conception of Mary — she’s conceived without sin, she’s born without sin, she lives her entire life without sin — so when she is a 13 or 14-year-old girl and is approached by the angel Gabriel with the announcement that she would be the mother of Jesus Christ, she gives her unconditional obedience of faith; she says yes to God’s plan. So she lives her life without sin (an example of this is her perpetual virginity) and at the foot of the cross she gives her consent to the sacrifice and sufferings of her Son and in a sense joins her suffering with his. The next time we see Mary is in the upper room with 120 disciples and she’s praying, according to Catholic theology, she’s contributing to the beginning of the church and then she continues to be both the mother and the teacher of the church. Her titles include Helper, Benefactress, Advocate, and Co-Mediatrix alongside her Son. These are very lofty titles and they’re also attitudes and realities of her that are not reflected in Scripture, so we see an authority that derives from Church Tradition with regard to Marian doctrine, which of course clashes with the Protestant view of authority, Sola Scriptura.

CS: What are ways we as Protestants often unfairly criticize Catholics?

GA: If we don’t understand truly what Catholics believe and what they engage in then we will find ourselves unjustly criticizing. The notion, for example, that in the mass today Jesus will be crucified for the 2,349,737,014th time is a misunderstanding of Catholic theology. Catholics believe that Jesus Christ died once on the cross, that crucifixion is re-presented in the mass today but it’s not another crucifixion; it’s one death of Jesus Christ not locked in space and time but through the eternality and atemporality of God, this sacrifice becomes re-presented at the mass today. That’s something that the vast majority of Protestants get wrong. Also the notion that Catholics have a fourth person, a fourth member of the Trinity, namely Mary, that’s completely wrong as well.

CS: Pope Francis recently made some interesting comments that he agreed with Martin Luther on justification, but what still separates Protestants and Catholics on this issue?

GA: The fundamental definition still separates us. So as Protestants, we believe that justification is a forensic act of God; it’s a legal declaration. God declares sinners not guilty because of the forgiveness they receive in Jesus Christ and totally righteous before God, not because they are righteous or have any inherent righteousness in themselves, but because the righteousness of Jesus Christ is imputed or credited to their account. That’s the Protestant view that was true in the 16th century and it’s still true today. The Catholic view of justification is not only the remission of sins, not only the forgiveness of sins, but also the sanctification and the renewal of the inner person. So justification according to Catholic theology conjoins forgiveness, sanctification, and regeneration, and we are still divided on this issue.