In an article entitled “5 differences between Catholic theology and the Gospel,” Jesse Johnson writes:

With Reformation Day this week, it is a good time to remind ourselves of what exactly the differences are between the Roman Catholic Church and Protestants. Certainly on just about every single area of theology there are differences, but here are what I think are the five most glaring and significant issues that separate the Catholic Church from the gospel of grace:

1) Justification

Evangelicals teach that sinners are justified on the basis of faith alone, and that ones’ faith is placed in the finished substitutionary work of Jesus on the cross, confirmed by his glorious resurrection, and that this is a gift based entirely on his grace. Finally, that justification is complete and total at the moment of our conversion, and that believers never grow more justified.

In contrast the Catholic church teaches that justification is a process that includes works (with those works “infusing” one’s faith), and that those works are the cause of the justification process. Beyond that, the Catholic Church teaches:

“If anyone says, that by faith alone the impious is justified; let him be anathema” (Council of Trent #9)

Or:

“If anyone says that the justice [or justification] received is not preserved and also not increased before God through good works but that those works are merely the fruits and signs of justification obtained, but not the cause of the increase, let him be anathema” (Council of Trent, 24).

2. The Pope as head of the church

For evangelicals, the church is made up of all of those who have been justified by God through faith. Local churches are led by elders, and each church is generally autonomous. Jesus Christ is the head of the church, and there is no authority over any local church on earth apart from Scripture. Elders and pastors are fallible in how they lead the church.

In the Roman Catholic teaching, the church is composed of laity and is led by those who have received the sacrament of Holy Orders (deacons, priests and bishops). The head of the church is the Pope, who when speaking authoritatively on matters relating to the church, is protected from the possibility of error concerning doctrine and morals of the church. Also, for anyone to be saved, they must be under the Pope’s authority:

“We declare, say, define, and pronounce that it is absolutely necessary for the salvation of every human creature to be subject to the Roman Pontiff” (Unam Sanctam, 1302).

3. Mass vs. communion

For evangelicals, communion is commemorative, and acts as a remembrance of the substitutionary atoning work of Jesus. The bread is symbolic of the body, and wine symbolic of the blood. There is nothing mystical or meritorious about it, but it is a means of grace and of provoking growth in godliness.

The Catholic Church teaches transubstantiation, that the bread and wine are transformed literally into the body and blood of Jesus. Thus in the mass, the priest calls Jesus down from heaven, and in the breaking of the bread Jesus is re-sacrificed. The mass is meritorious, as one of the seven sacraments, and it is a “true and proper sacrifice.” Here again is the council of Trent:

If any one saith that in the Mass a true and proper sacrifice is not offered to God; or, that to be offered is nothing else but that Christ is given us to eat; let him be anathema.”

As a side note, many of the Protestants and puritans made martyrs by the RCC went to their deaths over this issue. They considered participation in the Mass to be idolatry, and refused, and often were put to death for their refusal.

4. Mary

For evangelicals, Mary was Jesus’ mother, a sinner, and one who was saved from her sins by her faith in Jesus. We recognize a period of her life where she did not believe in Jesus (see, for example, Mark 3:30-33), but that by the time of Jesus’ death she had placed her faith in him as her Messiah. She had other children after Jesus, and died a physical death. She is to be admired as a woman of faith.

In the Catholic Church, Mary is an object of devotion—and in much of the world, she is an object of outright worship. It is normative to pray to her (consider, for example, the Hail Mary), and it is taught that she was sinless. In fact, the Immaculate Conception is the Catholic doctrine that Mary was conceived without a sin nature, thus she was not a recipient of Jesus’ redemption, but instead was a participant in that redemption. She was a perpetual virgin, and did not die a physical death, but was rather assumed into heaven, where she reigns now as the Queen of heaven and is herself Ineffabilis Deus (“ineffable God,” or “inexplicably divine”)

5. Purgatory

Evangelicals believe that there is no such place as purgatory, but that hell is real and heaven is obtainable only as a gift from God, through faith in Jesus’ sacrifice, and this is all of grace. For those who place their faith in Jesus, when they die they are immediately ushered into glory, where they will be in the presence of the Lord.

In Catholic theology, purgatory is where Catholics go when they die. Only those who are in a state of grace may go there, and once you have suffered for your non-mortal sins, you are made ready to see heaven. Thus purgatory is not eternal—but it is like hell in another way: purgatory involves both flames and suffering, and serves to make atonement for sins that you did not confess before you die. In many ways, Purgatory is the glue that holds the system together. Because it is a system where eternal judgment is based on works, and because sins are frequent and it is impossible to know and confess all of ones’ sins, purgatory is an essential piece of Catholic theology.

I give this list here simply because it always surprises me to find those that say “Catholics and Christians believe the same thing on the important issues, it is just in details where they differ.” Well, I suppose it matters what the “important issues are” but these five certainly touch on areas that are essential to the gospel.