Roman Catholicism is the largest single denomination of Christianity. At the end of 2014, the Catholic Church estimated 1.285 billion followers. Note that this is a Protestant blog (Protestantism is one of the other major sects of Christianity), so we will be taking a look at the key differences between Protestantism and Roman Catholicism, as their respective answers to the four worldview questions noted in earlier articles are quite similar.

Roman Catholicism claims that they alone have apostolic succession. What that means in simple terms is that according to Roman Catholicism, Jesus’s apostles (particularly Peter) inherited from Jesus authority over the global church. Peter served as head of the church (the first Pope) in Rome, and the succession of popes likewise serve as head of the church, with certain powers granted by Jesus. As will be explained later, Protestants have problems with several of those statements.

The History of the Protestant Reformation – Why We’re Not Catholic

In the early 1500s, the Roman Catholic church was well-established in the world. A few people, Martin Luther being one of the first, expressed dissatisfaction at certain beliefs and practices of the Roman Catholic church of the time. He wrote the ’95 Theses’, a list of 95 pronouncements that include condemnations against Roman Catholicism’s practices concerning indulgences. Indulgences were a method by which people could atone for themselves or others by their deeds. There were a couple major problems with this in the 1500s. People were able to earn indulgences on behalf of people who were already dead, which Martin Luther took issue with because he believed the Bible taught that we could not affect one’s eternal destination once they died. He also took issue with the fact that indulgences weren’t just earned via righteous actions – they could also simply be bought with money! Some preachers went around promising a quicker ascent to heaven for their recently passed loved ones if they interceded for them with a paid indulgence, which of course benefited the church.

Apart from indulgences, the ’95 Theses’ also asserts that the Pope is beneath Christ, stating the Pope’s limitations in that regard, and stresses the free availability of grace. As the story goes, the document was publicly posted in order to incite debate between Luther and others. The document was eventually marked as partially heretical by the Pope. Other people with similar concerns took a stand and throughout the 16th century, a growing movement took place. The Roman Catholic system in large part doubled down, organizing the Council of Trent in the mid 1500s to clarify its positions and refute many Protestant doctrines. While the system of indulgences continued, they were reformed in the latter half of the 16th century to make them much less susceptible to abuse by profit-seeking preachers.

Even though Luther wanted to correct the Catholic church from the inside rather than compete with it, Protestantism over time because a major branch of Christianity with more than 900,000,000 followers today, despite early persecution and charges of heresy from the (at the time) politically dominant Catholic church. Today, Protestants enjoy a less hostile reception by the Catholic church – in the mid 1900s, after centuries of being marked as heretics, they are today seen as fellow Christians who have indeed received salvation, although have chosen to be separate from the communion of the ‘one true apostolic church’ of Roman Catholicism. It should definitely be noted that Roman Catholicism and Protestantism are two denominations in the same religion, rather than two entirely separate religions. They do share the basic tenets generally required to identify a Christian, such as belief in Jesus as God’s son and our savior, the belief in the Bible as God’s direct word to us, the existence of heaven and hell, and so on. Nevertheless, many differences between Roman Catholics and Protestants still exist on points both major and minor, to the point that both denominations accuse the other of seriously misrepresenting or mishandling the word of God to the potential peril of their fellow believers. We’ll take a look at some more major differences here – the Pope, the Bible, how God’s grace is conferred, and the treatment of Mary and the saints.

Apostolic Succession (The Pope)

One of the largest differences between Catholics and Protestants is the recognition of the papal system. The head of Roman Catholicism is the Pope, who resides in the Vatican. Under the Pope is a system of regional churches, leaders, etc. According to Catholics, the office of the Pope is supported in the Bible, when Jesus says “on this rock I will build my church” in response to Peter’s declaration of Jesus as Christ (Matthew 16:17). To Catholics, this means that Peter was to play an instrumental role in the church, and Catholic tradition maintains Peter ruled the church from Rome after Jesus’s death and resurrection. To Protestants, the ‘rock’ means Peter’s testimony of Jesus as Christ, not Peter himself. In that interpretation, it simply means the church is built on the testimony of its believers.

The Pope is particularly contentious for the ability to declare new doctrine as infallible to the Catholic church. While this ability is not frequently used, Protestants do NOT acknowledge that the infallibility exists in the papal office at all. To a Protestant, nobody besides God Himself is infallible. In fact, there have been times when a Pope has been judged to have steered the church incorrectly by later Roman Catholics. Pope Francis, today’s Pope, has garnered controversy for being lukewarm at best about some matters of biblical fact. Back in April 2019, the previous Pope, Pope Benedict XVI, wrote a public statement condemning the current direction of the Roman Catholic church, raising the obvious question – if they disagree, which pope is right?

Biblical Canon

The Apocrypha is a set of books in the Catholic Bible that are not present in the Protestant Bible. These books were declared to be (infallibly) part of the Catholic Bible in the mid-1500s at the aforementioned Council of Trent, one of the Catholic councils that sought to define a variety of issues important to Catholics at the time. These 11 books have not been commonly accepted in the Protestant bible for a variety of reasons, most if not all of them referenced in our earlier article on how the books of the Bible were chosen. For some, they never claimed to be divinely inspired. For others, they introduce doctrines that go against those in the accepted Biblical canon. This is not to say that they are necessarily false in all aspects. In particular, First and Second Maccabees are useful for bridging the historical gap between the canonical Old and New Testaments, but they also introduce non-canonical beliefs such as purgatory.

God’s Grace

One of the most significant differences between Protestantism and Roman Catholicism is the nature of salvation and justification. Those terms are slightly different between Protestantism and Roman Catholicism. While Protestants believe we are ultimately justified (our sins covered before God) by Jesus’s sacrifice, apart from anything we can do besides having faith in Jesus’s power to have saved us from sin, the Catholic position requires observation of certain sacraments through which (according to them) grace is given. Instead of being just an outward result of one’s inner conversion to Christianity as in Protestantism, the sacraments (including baptism and holy communion) are means by which one OBTAINS grace – one is required to be baptized or at least intend to be baptized in order to be counted as saved (unless he or she does not actually know what baptism is, but still seeks to follow God).

Mary and the Saints

Roman Catholicism venerates Mary (the mother of Jesus) and saints (exceptionally pious people from church history). In the case of Mary, she is acknowledged within Roman Catholicism as having never sinned, was a virgin all her life, favored by God, assumed into heaven (taken up body and soul into heaven directly at the end of her life), is a mediator for us to Christ in heaven, and therefore deserves our prayers, as in the common Catholic prayer ‘Hail Mary’. Protestants can only readily affirm one of these points – that Mary was considered favored by God inasmuch as she was chosen to be the mother of Jesus. In pretty much all other respects, Mary was no greater than the rest of us. She was faithful, no doubt, but she sinned (In Luke, she acknowledges God as her savior, and brings sacrifices to the temple, both of which would be unnecessary if she didn’t sin). She also had other children (Matthew 13:55, 12:46), and in general died on Earth the same way as any other woman.


When delving into denominational differences like this, one must keep in mind to have a clear view of the depth of importance placed on them. First order differences are hugely important theological distinctions – if you don’t believe in them, you are not considered a Christian in most circles. One example would be not believing that Jesus is our savior – Christianity falters if you have no Christ. Second order differences are more denominational in nature, and the Roman Catholic distinctives discussed above generally fall into this category – taking up one view or the other won’t necessarily prevent salvation, although there can be (and usually is) a lot of spirited debate around these. The point we wish to end with, though, is that there are many genuine Christians in both Roman Catholic and Protestant camps. There are also, unfortunately, those in both camps that do not genuinely believe for various reasons. Both denominations, though, recognize their need for a Savior, who is Jesus Christ.

We can certainly say amen to that.


Recommended Resources:

About Roman Catholics and Evangelicals: Agreements and Differences by Norman L. Geisler and Ralph E. MacKenzie