When there is no enemy within, the enemies outside cannot hurt you. —Winston Churchill

In the Christian world, there is a massive assault on denominations and doctrinal divide. After all, we’re all believers and followers of Jesus Christ, right? If so, what’s the purpose of division? Why can’t we just all suck it up and get along? Doesn’t Jesus want us to be united (Philippians 2:2)? 1 Peter 3:8 says,

Finally, all of you, have unity of mind, sympathy, brotherly love, a tender heart, and a humble mind.

Let’s break this passage down, and see what we are really being commanded to do here. Clearly, Peter is saying in 1 Peter 3:8 that we, as Christians, are to be unified. But this begs the question: what exactly is “unity of mind?” Romans 16:17 says,

I appeal to you, brothers, to watch out for those who cause divisions and create obstacles contrary to the doctrine that you have been taught; avoid them.

The first thing we notice in this passage is Paul telling us exactly who it is that causes divisions in the church: those who create obstacles contrary to the doctrine that you have been taught. He then tells us to what? Avoid them! Essentially, he is telling us to divide from them–to have division from them. There is nowhere in Scripture that tells us it is acceptable to God to be spiritually united with those who hold to a false doctrine. We are, by nature of our salvation in Christ, spiritually separated from the world.

Undoubtedly, however, no believer is perfect in their doctrine–no denomination has it 100 percent right all of the time. So where do we draw the line?

The clearest line to be drawn is on the doctrine of justification. This is by far the most important doctrine in all of Scripture, and it’s the doctrine that many other doctrines rest on. It is the doctrine that if you have wrong, you cannot be saved, and you are not a Christian. If you have this doctrine wrong, you cannot, under any circumstances, be united with believers.

Simply put, the biblical doctrine of justification is by Grace alone, through faith alone, in Christ alone, according to the Scriptures alone, to the Glory of God alone. When this doctrine is rejected, salvation is passed up.

Let’s look further at these.

Grace alone through faith alone. 

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.

—Ephesians 2:8-9

Historically, Protestants and Evangelicals have defended this doctrine passionately. In contrast, the Roman Catholic Church has vehemently denied and rejected it. Canon 9 of the Roman Catholic council of Trent says “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, and that it is not in any way necessary that he be prepared and disposed by the action of his own will, let him be anathema.”

In Christ Alone.

And there is salvation in no one else, for there is no other name under heaven given among men by which we must be saved.

—Acts 4:12

Scripture teaches that it is only Jesus Christ who saves. There is no other entity–no other works of the flesh–that have any power to save us. In contrast, the Roman Catholic church teaches that the Church is essential to salvation and that it is through the sacramental system administered by the Church that is our means of grace. In Catholicism, it is only by the power of the priestly system with the pope at the head that you can be absolved from your sins. The trust is not solely in the finished work of Christ on the cross, but also in man. God is very clear that he will not share His glory with any other, be it man or idol (Isaiah 42:8).

According to the Scriptures Alone.

Roman Catholics officially hold that Church tradition is equal with Scripture, however, in reality, you find that Scripture is generally twisted and contorted to conform to the councils, and to the mandates of the papal system. A wide variety of Catholic traditions, including that of the doctrine of justification, are in direct conflict with the teachings of Scripture, yet they hold to the teachings of the tradition anyway. In contrast, Protestants and Evangelicals have historically stood on the Word of God as the final authority. The Scriptures themselves testify to the authority and sufficiency of themselves. 2 Timothy 3:16-17 says,

All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work.

To be “breathed out by God” is to be written under the inspiration of the Holy Spirit. This passage clearly teaches that the Scriptures are sufficient to make the man of God complete, and equipped for every good work.

To the Glory of God Alone. 

This is where it all ends. Bible-believing Christians who have been saved by the grace of God understand that man was created for one purpose alone–to Glorify God. God did not create us because he was lonely and needed a friend. He did not create us to glorify us. He created us for the sole purpose of displaying his attributes; His holiness, His righteousness, His love, His wisdom, His power, His mercy, His justice … and His wrath. To think that we can disregard His Word, and add to it, or subtract from it is, to say the least, boastful, and causes us to miss out on the partaking of His glory through His Son, Jesus Christ. It is Christ that is the ultimate display of God’s glory, and it is only through Christ that we can share in His eternal glory.

Drawing the Line.

While there are many questionable doctrines, teachings, and heresies that are pervasive in the professing Church, not all of them are damnable. This is, to say, that not all false beliefs will cause you to spend eternity in Hell. This is why Baptists and Presbyterians, for example, can fellowship, even though we have significantly different beliefs regarding baptism and ecclesiology. If you hold to the correct understanding of salvation, and you have been saved by grace alone, through faith alone, then you are a functioning member of the body of Christ and should be treated as such. Of course, debate and discussion, correction and reproof, about the doctrines should still be had, but fellowship should not necessarily be cut off unless it interferes with a proper understanding of justification.

The Doctrine of Justification rests on a proper understanding of who God is, who the Father, the Son, and the Holy Spirit are, and what God has done for us through his Son, Jesus Christ. An improper understanding of the Trinity, for example, will lead to an improper understanding of justification. An improper understanding of the deity of Christ will cause a false understanding of salvation. A rejection of Scripture and a wrong understanding of God’s grace will ultimately lead to a compromised understanding of how Jesus served as our propitiation, and how his righteousness has been imputed to us who believe. This is why heresies regarding these essential doctrines are considered damnable.

But even if we or an angel from heaven should preach to you a gospel contrary to the one we preached to you, let him be accursed.

—Galatians 1:8

This is why we cannot stand with Roman Catholics, Modalists, Prosperity Gospel preachers, many Charismatics, and adherents to doctrines that pervert the grace of God and reject the doctrine of the penal substitutionary atonement. Jude 1:4 says these people who deny our Master are condemned. Scripture is very clear that we should not associate with these people.

But now I am writing to you not to associate with anyone who bears the name of brother if he is guilty of sexual immorality or greed, or is an idolater, reviler, drunkard, or swindler—not even to eat with such a one.

—1 Corinthians 5:11

God is insistent that we not promote the false teachings in the church by associating with known false converts–people who pervert the grace of God. By doing so, we lend our credibility as true Christians to those who corrupt the Doctrine of Justification. Even if they say they don’t hold to the official teachings of their church, their denominational affiliation is still an expression of their faith, and we must treat them accordingly. God calls believers out of their idolatry; the Holy Spirit does not allow the saved to wander around aimlessly rejecting Him.

While friendship with the world is certainly forbidden, friendship with false teachers and idolatrous religious systems, like Roman Catholicism, is far worse in the eyes of God. We cannot, under any circumstances, stand with them to advance any spiritual enterprise.

We must draw the line at Justification.