The Bible is unambiguous in teaching that God’s people are not to take spouses who do not profess the true religion. In the Old Testament, God forbade the Israelites from intermarrying with those outside the covenant community, warning that those who do so will have their hearts turned away from him to serve other gods (see Deut. 7:3–4). Likewise, the New Testament makes it clear that Christians are only permitted to marry “in the Lord” (1 Cor. 7:39). This makes good sense when we consider the role that marriage plays in the spiritual edification of spouses and in the Christian nurture of children. How can a husband and wife live together as “heirs . . . of the grace of life” (1 Pet. 3:7) when one of them does not have title to that inheritance through the grace of justification (see Titus 1:4–7)? How can a couple raise their children “in the discipline and instruction of the Lord” (Eph. 6:4) when they do not share the same faith in the Lord?
While the Bible clearly forbids Christians from marrying non-Christians, one question that sometimes arises is whether or not Christians who belong to churches that preach the biblical gospel should be open to the possibility of marrying Roman Catholics. After all, Reformed churches have historically accepted Roman Catholic baptism as a valid Christian baptism, pointing out that it is done in the name of the triune God and that the efficacy of baptism does not depend on the merit of the one who administers it but on God, the one who has instituted it. Furthermore, while the Roman Catholic Church has significantly departed from the biblical gospel in its official teachings, we grant that there can be individuals in the Roman Catholic Church who have saving faith in Christ. In light of this, why can’t a Reformed or Evangelical Christian consider marrying a Roman Catholic who appears to have saving faith in Christ? Why does the Westminster Confession of Faith include “papists” among those whom Christians are forbidden to marry under the biblical imperative to marry “only in the Lord” (see WCF 24.3)?
One way of addressing this question is to think through what it means to make a profession of faith in Jesus Christ. According to the Bible, a profession of faith in Christ is not merely a private transaction between the individual believer and God. A profession of faith in Christ needs to be public and accountable to the oversight of church leaders. This is a good and necessary inference from Scripture, derived from passages such as these:
Pay careful attention to yourselves and to all the flock, in which the Holy Spirit has made you overseers, to care for the church of God, which he obtained with his own blood. (Acts 20:28)
Fight the good fight of the faith. Take hold of the eternal life to which you were called and about which you made the good confession in the presence of many witnesses. (1 Tim. 6:12)
Obey your leaders and submit to them, for they are keeping watch over your souls, as those who will have to give an account. Let them do this with joy and not with groaning, for that would be of no advantage to you. (Heb. 13:17)
These texts make it clear that Christ does not merely rule over his people inwardly in their hearts. He also rules over us outwardly through the ministry of those whom he appoints to keep watch over our souls. This is why the authority to admit and exclude people from the sacrament of the Lord’s Supper resides not in individual believers but in the church, acting through its officers.
The idea that a profession of faith in Christ needs to be public and accountable goes against the grain in our intensely individualistic culture. Many in our day understand faith as a fundamentally personal matter between an individual and God. The problem with this way of thinking is that it leaves no way of discerning whether a person is believing in Christ as he is revealed in the gospel or is believing in the sort of thing that the apostle Paul described as “a different gospel,” a gospel of human imagining that is really no gospel at all (see Gal. 1:6–9). In other words, if we make faith into an essentially private matter we create a situation in which Christianity can no longer have any objective meaning, because it can be defined in whatever way each individual believer wants to define it.
A Roman Catholic is someone whose profession of faith is subject to the oversight of the Roman Catholic Church. The reason why this is a problem is because the Church of Rome has officially condemned the biblical doctrine of justification by faith alone. This was done most definitively at the Council of Trent, which was held from 1545 to 1563. While the sixteenth century was a long time ago, Rome’s understanding of church tradition makes the pronouncements that were made at Trent just as binding today as they were when they were first made. Moreover, these pronouncements are confirmed in the contemporary Catechism of the Catholic Church. When we compare what was said at Trent with what is said in the Bible, it is clear that, as an institution, Rome itself officially teaches a different gospel, a gospel of justification by faith plus works.
At Trent, Rome insisted that a believer’s good works are not to be understood as the fruit that necessarily flows from justifying faith, but as a means by which a person merits favor from God. Among the many decrees issued by Trent, Canon 9 declares,
If anyone says that the sinner is justified by faith alone, meaning that nothing else is required to cooperate in order to obtain the grace of justification . . . let him be anathema.
Similarly, Canon 24 says,
If anyone says that the righteousness 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.
And Canon 32 adds,
If anyone says that the good works of the one justified are in such manner the gifts of God that they are not also the good merits of him justified; or that the one justified by the good works that he performs by the grace of God and the merit of Jesus Christ, whose living member he is, does not truly merit an increase of grace, eternal life, and in case he dies in grace the attainment of eternal life itself and also an increase of glory, let him be anathema.
Stated positively, Trent declared that the good works done by a believer are meritorious and therefore contribute to, and even increase, his righteous standing before God. Compare this with the teaching of Scripture:
For by works of the law no human being will be justified in his sight, since through the law comes knowledge of sin. But now the righteousness of God has been manifested apart from the law, although the Law and the Prophets bear witness to it— the righteousness of God through faith in Jesus Christ for all who believe. For there is no distinction: for all have sinned and fall short of the glory of God, and are justified by his grace as a gift, through the redemption that is in Christ Jesus, whom God put forward as a propitiation by his blood, to be received by faith. This was to show God’s righteousness, because in his divine forbearance he had passed over former sins. It was to show his righteousness at the present time, so that he might be just and the justifier of the one who has faith in Jesus. Then what becomes of our boasting? It is excluded. By what kind of law? By a law of works? No, but by the law of faith. For we hold that one is justified by faith apart from works of the law. . . . Now to the one who works, his wages are not counted as a gift but as his due. And to the one who does not work but believes in him who justifies the ungodly, his faith is counted as righteousness, just as David also speaks of the blessing of the one to whom God counts righteousness apart from works: “Blessed are those whose lawless deeds are forgiven, and whose sins are covered; blessed is the man against whom the Lord will not count his sin.” (Rom. 3:20–28; 4:4–8)
For by grace you have been saved through faith. And this is not your own doing; it is the gift of God, not a result of works, so that no one may boast. For we are his workmanship, created in Christ Jesus for good works, which God prepared beforehand, that we should walk in them. (Eph. 2:8–10)
For his sake I have suffered the loss of all things and count them as rubbish, in order that I may gain Christ and be found in him, not having a righteousness of my own that comes from the law, but that which comes through faith in Christ, the righteousness from God that depends on faith. (Phil. 3:8–9)
Paul’s contrast between “wages” and “gift” in Romans 3–4 makes it clear that human beings can never do anything to merit God’s grace. If justification is a freely given gift, then the believer’s good works cannot in any sense contribute to his righteous standing before God. Moreover, the quotes from Ephesians and Philippians both stress that salvation is in no sense based upon anything that we do or upon any righteousness that we ourselves possess.
Roman Catholics typically point to this passage from James to support their position:
But someone will say, ‘You have faith and I have works.’ Show me your faith apart from your works, and I will show you my faith by my works. You believe that God is one; you do well. Even the demons believe—and shudder! Do you want to be shown, you foolish person, that faith apart from works is useless? Was not Abraham our father justified by works when he offered up his son Isaac on the altar? You see that faith was active along with his works, and faith was completed by his works; and the Scripture was fulfilled that says, “Abraham believed God, and it was counted to him as righteousness”—and he was called a friend of God. You see that a person is justified by works and not by faith alone. (James 2:18–24)
If those verses mean what Roman Catholics say they mean, then James is in conflict with Paul, who writes the following in his letters to the Romans and Galatians:
What then shall we say was gained by Abraham, our forefather according to the flesh? For if Abraham was justified by works, he has something to boast about, but not before God. For what does the Scripture say? “Abraham believed God, and it was counted to him for righteousness.” (Rom. 4:1–3)
Yet we know that a person is not justified by works of the law but through faith in Jesus Christ, so we also have believed in Christ Jesus, in order to be justified by faith in Christ and not by works of the law, because by works of the law no one will be justified. . . . Let me ask you only this: Did you receive the Spirit by works of the law or by hearing with faith? Are you so foolish? Having begun by the Spirit, are you now being perfected by the flesh? Did you suffer so many things in vain—if indeed it was in vain? Does he who supplies the Spirit to you and works miracles among you do so by works of the law, or by hearing with faith— just as Abraham “believed God, and it was counted to him as righteousness”? (Gal. 2:16; 3:2–6)
If we were to insist that “justified” in James 2 means the same thing that it means in these passages from Paul, we would make God’s Word contradict itself. This is why the term needs to be understood in light of the specific contexts of these letters, taking into account the different problems that were being confronted by the authors. In Romans and Galatians, Paul confronted legalism by saying that faith, apart from works, is the sole instrument of justification. In James, the writer confronted antinomianism by saying that good works are the evidence that a person has true justifying faith. James is saying that good works are necessary for salvation in an evidentiary sense, while Paul is saying that they are not necessary in an instrumental sense. James is saying that saving faith bears the fruit of good works in a believer’s life, while Paul is saying that these works do not merit anything from God. These teachings are in direct conflict with what was decreed at Trent. As we have already seen, this is precisely what was condemned at that council.
Because of its erroneous teaching on the question of how a person can be made right with God, the Church of Rome is not capable of evaluating an individual’s profession of faith in Christ. A person who belongs to the Church of Rome has not had his or her profession of faith examined by a church that teaches the biblical gospel. While an individual Roman Catholic’s faith may or may not rest upon Christ alone as he is revealed in the gospel, it is not up to some other individual to make that determination. On the contrary, this responsibility belongs to the church and needs to be carried out by its officers, because Christ has authorized the church to distinguish between believers and unbelievers through its preaching and discipline. In light of this, it follows that if a person belongs to a church that explicitly denies essential aspects of the biblical gospel, the credibility of that person’s profession of faith is called into question. This is one reason why a Reformed or Evangelical Christian should not marry a Roman Catholic. To do so is to become yoked to someone whose Christian profession is not accountable to a true church, and is also under the authority of an institution that officially condemns the biblical gospel.
A second reason why a Reformed or Evangelical Christian should not marry a Roman Catholic has to do with the practical problems caused by such a union. A couple cannot help each other grow in the grace and knowledge of Christ when they belong to traditions that have such serious disagreements over fundamental aspects of the Christian faith. Neither can such a couple pass on a biblically robust faith to their children. When a Roman Catholic marries a non-Catholic spouse, the latter has to pledge to raise his or her children in the Church of Rome. How can a Reformed or Evangelical Christian make such a pledge? Furthermore, when a couple dismisses as inconsequential the differences between historic Protestantism and Roman Catholicism, they inevitably point to the common ground that they have in their subjective religious experiences, their moral code, and the aesthetic qualities that they associate with genuine piety (perhaps the informality and contemporaneity that are characteristic of Evangelicalism, or perhaps the rites and rituals that are characteristic of traditions that feature a “high” liturgy). The problem with finding common ground only in those things is that it is the doctrinal elements of Christian faith that make it distinctively Christian. The gospel is not an experience, a set of moral teachings, or an aesthetic style (though it does have ramifications in these areas). At its heart, the biblical gospel is the revelation of the righteousness from God that is received by faith alone in Christ alone. Any conception of Christianity that sets that message aside as unimportant is a different gospel. And as the Bible makes clear, a different gospel has no power to save.
 There have been a few exceptions, most notably among southern Presbyterians in nineteenth-century America. See the overall survey provided in J.V. Fesko, Word, Water, and Spirit: A Reformed Perspective on Baptism (Grand Rapids: Reformation Heritage, 2010), 368–94.
 In the words of James Buchanan, “Do we then deny the possibility of pardon and acceptance with God within the Church of Rome? God forbid! What we deny is that any sinner was ever justified, there or elsewhere, by his own righteousness; and we reject the Romish doctrine of justification, as having a tendency to lead men to rely on their own good works rather than on the finished work of Christ.” The Doctrine of Justification: An Outline of Its History in the Church and of Its Exposition from Scripture, (1867; repr., Edinburgh: Banner of Truth, 1977), 149.
 It is worth noting that the pronouncements made at Trent actually marked a change for Rome, since prior to that point it had tolerated other views, at least officially. In the words of one historian, “One effect of Protestantism was that the Roman Catholic Church became less inclusive. Heretofore it had permitted diversity of views on some of the issues raised by Protestants. Now it felt itself constrained to state its convictions more precisely. The definitions of dogma framed by the Council of Trent . . . were consciously directed against Protestant teachings. They ruled out opinions held by some who had remained within the Roman Communion.” Kenneth Scott Latourette, A History of Christianity, volume 2: Reformation to the Present, (New York: Harper and Row, 1975), 840.
 In spite of the softer and more positive tone that was expressed towards Protestants at the Second Vatican Council (1962–1965), Rome's official teachings on justification remain the same as those expressed at Trent.
 See especially sections 1987–2011.
Andy Wilson is the pastor of Grace Presbyterian Church (PCA) in Laconia, New Hampshire. Ordained Servant Online, February 2018.