One of the chief criticisms of Protestantism is the lack of unity among the various Protestant denominations. There are hundreds of Protestant denominations, all claiming to follow the Bible alone, but they all contradict each other. There are Lutherans, Baptists, Methodists, Episcopalians, Pentecostals, Presbyterians, and many others, but no two denominations totally agree with each other. Their usual answer is that while they disagree on many issues, they agree on the essentials (that Jesus is Lord and Savior and that we are saved through Him by faith alone are two of the most common beliefs that are considered essential). The problem, however, is that Scripture repeatedly tells us to be one unified body, and it never mentions makes a distinction between the "essentials" and the "nonessentials." Let's take a look at what Scripture says about the unity of the Church.
"When the Spirit of truth comes, he will guide you into all the truth" - John 16:13
All truth. Not some truth, not truth about the essentials, but the Holy Spirit teaches the Church ALL of the truth that God has revealed. This is why Paul can say that the Church is the "pillar and bulwark of the truth" (1 Timothy 3:15). The Church holds up the truth and teaches it to the world without error. Can Protestantism claim to be the pillar and bulwark of the truth? If so, it is a poor pillar indeed, supporting various contradictory "truths."
"I ask not only on behalf of these, but also on behalf of those who will believe in me through their word, that they may all be one. As you, Father, are in me and I am in you, may they also be in us, so that the world may believe that you have sent me. The glory that you have given me I have given them, so that they may be one, as we are one, I in them and you in me, that they may become completely one, so that the world may know that you have sent me and have loved them even as you have loved me." - John 17:20-23
Jesus prayed to the Father for the unity of all of His future followers. Not only does He want us all to be one, but He wants us all to be one as He and the Father are one! He and the Father are one God, one being, and we are all to be one body of Christ (1 Corinthians 12:18-21). In fact, Paul even says that we are all parts of one another (Romans 12:4-5), which is as close as we will ever get to being one as Jesus and the Father are one. But what does this mean? How exactly are we to be one as Jesus and the Father are one?
"I urge you, brothers and sisters, to keep an eye on those who cause dissensions and offenses, in opposition to the teaching that you have learned; avoid them." - Romans 16:17
"Now I appeal to you, brothers and sisters, by the name of our Lord Jesus Christ, that all of you should be in agreement and that there should be no divisions among you, but that you should be united in the same mind and the same purpose." - 1 Corinthians 1:10
"There is one body and one Spirit, just as you were called to the one hope of your calling, one Lord, one faith, one baptism, one God and Father of all, who is above all and through all and in all." - Ephesians 4:4-6
"Only, live your life in a manner worthy of the gospel of Christ, so that, whether I come and see you or am absent and hear about you, I will know that you are standing firm in one spirit, striving side by side with one mind for the faith of the gospel" - Philippians 1:27
"If then there is any encouragement in Christ, any consolation from love, any sharing in the Spirit, any compassion and sympathy, make my joy complete: be of the same mind, having the same love, being in full accord and of one mind." - Philippians 2:1-2
"After a first and second admonition, have nothing more to do with anyone who causes divisions" - Titus 3:10
From these passages, we can clearly see that Christ's Church is to be one, without any divisions, but that's the exact opposite of Protestantism! With disagreements about infant baptism, baptismal regeneration, the Eucharist, Church hierarchy, Christ's atonement, free will, and other issues, the one trait that characterizes Protestantism is divisions and lack of unity. Protestants do not have "one mind," Protestantism is not "one faith," and Protestants do not heed Paul's advice to avoid divisions. Nowhere does Scripture say that we are to agree on just the "essential" doctrines but not the "nonessential" ones; in fact, Scripture never even makes that distinction! On the contrary, we see Scripture's repeated affirmation that we are to be, without exception, one united body without divisions.
"Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, and teaching them to obey everything that I have commanded you. And remember, I am with you always, to the end of the age." - Matthew 28:19-20
Here, Jesus instructs His apostles to preach the Gospel and to teach everything that He taught, not just the "essentials" of His teaching. Once again, there is no distinction between the "essential" doctrines and the "nonessential" doctrines. Everything is important, and everything must be obeyed.
"But some believers who belonged to the sect of the Pharisees stood up and said, 'It is necessary for them to be circumcised and ordered to keep the law of Moses.' The apostles and the elders met together to consider this matter." - Acts 15:5-6
Here, we see that the early Church was DEFINITELY not Protestant. If it were, the Pharisaical Christians would've just left and started their own denomination, but they still would've agreed on the "essentials." However, this isn't what they did. Rather, the leaders of the Church got together and came to a decision that was to be obeyed by Christians everywhere (Acts 16:4). Rather than choose to disagree on this seemingly "nonessential" doctrine, the Church leaders made a binding decision that all Christians had to follow and kept the Church unified.
"Now the Spirit expressly says that in later times some will renounce the faith by paying attention to deceitful spirits and teachings of demons, through the hypocrisy of liars whose consciences are seared with a hot iron. They forbid marriage and demand abstinence from foods, which God created to be received with thanksgiving by those who believe and know the truth." - 1 Timothy 4:1-3
Here we see Paul flat-out contradicting the Protestant belief that all you need to believe are the "essentials." He says that those who "forbid marriage and demand abstinence from foods, which God created to be received with thanksgiving" have been tricked by demons and "renounce the faith." Now, not letting people marry or eat certain foods seem much less essential to Christianity than things like baptism, the Eucharist, Christ's atonement, and Church hierarchy, but Paul still considers them to be essential! Again, we see Scripture affirming that Christians must be one united, undivided body, believing EVERYTHING that God has revealed to us.
But what about the Catholic Church? Are we really as united as we say we are? Are Catholics one united, undivided body that believes everything that Christ taught? No. So doesn't my argument backfire on the Catholic Church as well because we are not all united? No. Everybody who is totally loyal to the Church is united as Christ wants us, but there are some Catholics who don't believe everything that the Church teaches. We know that those Catholics are going against what both Scripture and the Church teach; they are not in full communion with the Church. But those Catholics who are in full communion with the Church are united in the truth, as Scripture says we should be. There will always be Catholics who are not totally faithful to the Church, as Jesus said (Matthew 13:36-43), but that does not take away from the unity of those who are faithful to the Church.
