The Protestant Reformation rejected central Catholic beliefs and practices regarding the nature of Revelation, justification, and the sacraments. The general contention was, and continues to be, that such beliefs and practices have no foundation in biblical Revelation and are even contrary to it. The Catholic Church has addressed these issues authoritatively and definitively, most notably in the Council of Trent and the Second Vatican Council. Nevertheless, many must address Protestant objections to the Catholic faith at a personal level: whenever they are raised by a friend, relative, colleague, missionary, or group. Oftentimes, they may not be sure how to answer them. Some might even begin to suspect that the objections are sound. At the same time, some Protestants are questioning the validity of the same objections and wondering whether they should become Catholics.

Those grappling with these issues will often feel the need to study the biblical, theological, and historical grounds for the contested Catholic teachings. Catholic apologetics gathers the evidence and outlines the arguments systematically.

In this interview, Trent Horn selects and discusses five books of apologetics that can help those grappling with Protestant objections to the Catholic faith.

Trent Horn is a staff apologist and speaker for Catholics Answers, and adjunct professor of apologetics at Holy Apostles College. He specializes in teaching Catholics to graciously and persuasively engage those who disagree with them. He can be heard on the radio program Catholic Answers Live and on his own podcast, The Counsel of Trent. He has written for The National Catholic Bioethics Quarterly, and is the author of nine books, including Answering Atheism, The Case for Catholicism, and Why We’re Catholic: Our Reasons for Faith, Hope, and Love.

Catechism of the Catholic Church
by John Paul II
The Case for Catholicism: Answers to Classic and Contemporary Protestant Objections
by Trent Horn
The Apostolic Fathers
Teaching with Authority: How to Cut Through Doctrinal Confusion & Understand What the Church Really Says
by Jimmy Akin
Pope Peter: Defending the Church's Most Distinctive Doctrine in a Time of Crisis
by Joe Heschmeyer

Five Books for Catholics may receive a commission from qualifyng purchases made using the affliate links in this post.

What is apologetics?
Apologetics comes from the Greek word apologia which means to give a defence of something, typically in a court of law. When we refer to the faith, apologetics is the branch of theology that is dedicated to giving a rational defence of the Catholic faith.

Theology is a science and if apologetics is a subfield of theology, presumably it too is a science and relies exclusively on rigorous argumentation. To some extent, however, it is also an application of the art of rhetoric, where one selects the reasons most likely to persuade the addressee. Is it a bit of both: science and rhetoric?
It depends on the focus of the one engaged in apologetics. Some publish peer-reviewed journals or academic books on apologetics. They are focused primarily on answering objections, mounting forth evidences for the faith, putting forward arguments, compiling the evidence. They are focused more on the accumulation of knowledge.

However, many who engage in apologetics, especially lay people, are talking to friends and family. Rhetoric is a very important part of this.

In this regard, apologetics is similar to evangelism. In evangelism it is not just what you say, but how you say it. Similarly, in apologetics you need to appeal to people's sense of ethos, pathos, and logos: authority, emotion, and logical argumentation.

Where does apologetics fit into the broader sweep of evangelization and catechesis?
Apologetics is certainly not identical to evangelism or catechesis. Evangelism is sharing the Good News of salvation through Jesus Christ and his Church. Catechesis is the greater instruction of those who have been evangelized. Literally, "catechesi"s means to sound down: to build a foundation for the person who has accepted the Good News about faith in Jesus Christ and his Church. In some cases, you can catechize without apologetics by simply presenting the Church’s teaching. In other cases, people will have objections. It may be an objection to the Gospel. It may be a question about some Church teaching that does not make sense to them or about which they have heard opposing arguments from non-Catholics. Here, apologetics complements what we do in evangelization and catechesis.

"The most fundamental issue dividing Catholics and Protestants is the doctrine of sola Scriptura."

Particularly since Vatican II, the Catholic Church has encouraged ecumenical dialogue. Some, therefore, may suspect that making the case for the Catholic faith to convert Protestants rather than to defend one’s own faith is triumphalist, runs contrary to the spirit of ecumenism, and no longer has a place in the Church. Do you agree?
No, I strongly disagree with that. The council never condemned apologetics, namely, providing reasons for the Catholic faith, whether to reassure Catholics in their faith or to encourage a non-Catholic to fully embrace the faith of the Church.

Pope Francis and Pope Benedict XVI have condemned proselytism: the use of manipulative, coercive, or dishonest tactics in evangelization to encourage people to become Catholic.

Apologetics can be carried out in a triumphal and obnoxious way. However, it can also be carried out in the spirit of ecumenism.

For example, Catholics and Lutherans have made great strides since the Reformation and the Second Vatican Council to find common ground on the doctrine of justification by faith. Even Pope Benedict XVI claimed that the formula, “by faith alone,” can be valid if faith is not divorced from charity, as Paul says in Galatians 5:6. That is an example of ecumenism. Ecumenism brings Catholics and a non-Catholic party closer together, but never fully together. Apologetics helps bridge that final gap between the two.

Obviously, one should make the case for the Catholic faith not just with conviction, but also with modesty, charity, and a spirit of prayer, without being pushy, overbearing, or arrogant. However, St. Peter tells us to give a reason for the hope that is in us to those who ask (1 Peter 3:15). Should we only ever defend the Catholic faith to those who ask or sometimes take the initiative?
Well, we certainly should take the initiative, but we do not have to start off with an argument. What we can do when engaging a non-Catholic is just ask them questions. “What do you think about God? Who do you think Jesus Christ is? What do you think of the Catholic Church? Do you believe that the Catholic Church contradicts the Bible? Why do you think that?”

In asking these questions, we are not being antagonistic. We are taking the initiative without either proselytizing or browbeating. We are just asking questions and prompting the other person to rethink their worldview.

Traditionally, Catholic theologians have distinguished between three stages of apologetics, depending on whether one is addressing atheists, non-Christian religions, or separated Christian brethren: demonstrating the truth of religion (demonstratio religiosa), the truth of Christianity (demonstratio christiana), and the truth of Catholicism (demonstratio catholica). Addressing Protestant objections falls within this last stage. Nevertheless, there are doctrinal differences between each of the main Protestant denominations. An Anglican does not share all the Presbyterian’s objections to Catholicism, and vice versa. Moreover, we know what the main objections regard the nature of Revelation, justification, and the sacraments. For Protestants Revelation is transmitted through Scripture alone (sola Scriptura), we are justified by responding to grace through faith alone (sola fide), and the only priestly mediation between God and man is that exercised by Christ alone (solus Christus). Is this an accurate summary of the main issues or is one of these issues more fundamental than the others?
That is an accurate summary.

The most fundamental issue dividing Catholics and Protestants is the doctrine of sola Scriptura.

On the doctrine of sola fide, we have gained a lot of ground in reaching a common understanding of justification by faith. The Catechism is very clear that man can do nothing to merit initial salvation (n. 2010). When we first receive salvation, it is by grace alone and not merited by any work we have done. It is not even by faith. An infant who is baptized does not have their own faith, even though their parents do have faith when they seek baptism for their child. Rather, there is nothing that merits initial salvation. We can agree with Protestants, therefore, when they say that we are saved by grace alone.

However, that does not mean human beings do not cooperate with God to remain united with him until our final salvation.

While it is important to look at this, sola Scriptura is the fundamental dividing point. Protestants will create a litmus test. They hold that a doctrine is not obligatory and maybe even impermissible unless is not found explicitly in Scripture. However, that is not what Scripture teaches. Using sola Scriptura as a means of discerning doctrine leaves one with an incredibly truncated faith, with essential elements missing, and leads to contradictory articulations of the faith among the various Protestant denominations.

How did you become involved in apologetics?
I became involved in apologetics as a convert in high school. I came to Christianity and then investigated different churches. So, I had to answer the objections for myself during high school.

Then I volunteered for a youth group and did apologetics in it to help others in their faith. Apologetics was a hobby that I really enjoyed. Moreover, I did a lot of work in the pro-life movement. Then, in 2012, I was invited to join Catholic Answers.

Three of your five recommended books are fairly recent publications from Catholic Answers. However, there is a centuries long tradition of Catholic literature that addresses Protestant objections. There are even doctors of the Church, such as St. Francis de Sales and St. Robert Bellarmine, who wrote notable works. Which books stand out as classics on the subject that are still worth studying but also accessible to modern readers?
Certainly, there are many. For example, the Sheed and Ward Catholic Evidence Training Outlines are very helpful. If you go back even further, ironically Henry VIII's Defence of the Seven Sacraments can be very helpful.

As you said earlier, some Protestants are much closer to Catholics in their theology and will have some important insights.

However, going back, St. Francis de Sales’s The Catholic Controversy is certainly a classic. Another is St. John Henry Newman’s An Essay on the Development of Doctrine. It is an invaluable resource.

While these classic works are very important, I would recommend studying them after building a foundation with more contemporary works, such as the five books I have selected here (though there is one classic work in the list). The newer works respond to the newest challenges, whereas sometimes it can be difficult to parse the precise argument of the older works—such as those by Newman, Francis de Sales, or Bellarmine—if you are not familiar with the historical context. For a new reader of apologetics, it can be interesting to read them. For sure. However, it can be difficult to form a coherent response to Protestantism from these works. It is better to build a foundation with more contemporary works and then enrich the foundation by going to the classic works later.