Question: What do you have to believe (what is the minimum) in order to be a Christian? Put another way, at what point does someone believe something that puts them outside of Christianity?
Answer: At the most basic level, in order to be a Christian, one must believe in Jesus Christ. The Bible says, “Believe in the Lord Jesus and you will be saved” (Acts 16:31). That is essentially what the thief on the cross did in Luke 23:42 when he said, “Jesus, remember me when you come into your kingdom.” Jesus replies to him, “Truly, I say to you, today you will be with Me in paradise” (Luke 23:43). How much did the thief on the cross know? We’re not told, but he knew enough. He knew that Jesus was his only hope for salvation and that Jesus was King.
So let’s go back to the basic truth that one must “believe in the Lord Jesus and you will be saved.” What does it mean to “believe?” In the history of the Christian church, the notion of faith has been broken down into three elements: (1) You must believe in something, your faith must contain content; (2) You must assent to the truth of the content of your faith; (3) You must trust in the object of your faith, your faith must alter your behavior. So when Paul says, “Believe in the Lord Jesus,” there is some content behind those words. The basic content of our faith is aptly summarized in the Apostles’ Creed:
“[I believe] in Jesus Christ [God the Father’s] only-begotten Son, our Lord: who was conceived by the Holy Spirit, born of the Virgin Mary, suffered under Pontius Pilate, was crucified, died, and buried; He descended into hell; the third day He rose from the dead; He ascended into heaven, and sits at the right hand of the Father Almighty; from there He shall come to judge the living and the dead.”
This is the content of our faith regarding Jesus Christ. Second, you must believe this to be true. An atheist may know the content of the Christian faith (maybe better than some Christians), but he/she does not believe it to be true. Third, you must trust. The Heidelberg Catechism, in Q22, calls this a “hearty trust.” This hearty trust motivates us into action. Now that you know and believe the truth of Jesus Christ, what now shall you do? A hearty trust springs into action.
One thing we need to keep in mind is that our faith in Christ isn’t (or shouldn’t be) a static thing. By that I mean, our faith, what we know and believe regarding Jesus, isn’t frozen in time, but rather it grows as we attend church and read our Bibles. A new Christian may not know all of the intricacies of the atonement or be able to state clearly the doctrine of the Trinity or be able to articulate what is meant by the hypostatic union (the union between the human and divine natures of Jesus). But a new Christian will certainly know that Jesus died for their sins and that if they believe in Jesus they will not perish, but have eternal life. As with any human child, it is the duty of their parents to instruct and train their child as they grow up. That’s why the Great Commission (Matthew 28:18-20) says it’s the mission of the church to make disciples (i.e., “learners”) by baptizing and teaching them all that Jesus commanded.
So because we need to grow in our knowledge of the faith (i.e., the content of the Christian faith), we may not believe correct things or we may not articulate what we believe correctly. Let’s use the example of the Trinity because this is one that trips up even experienced Christians. The doctrine of the Trinity states that God exists as One Being, in essence, manifested in three distinct persons, Father, Son, and Holy Spirit. The Father is God, the Son is God, and the Holy Spirit is God. The Father is not the Son, nor is the Son the Holy Spirit, nor is the Holy Spirit the Father. Now if you ask the average Christian to explain how this can be so, invariably you get analogies like this: The Trinity is like water, just as the Trinity is Father, Son, and Holy Spirit, water can exist as solid, liquid, or gas. The problem with that analogy is that water cannot exist as solid, liquid, or gas at the same time under the same conditions. Theologically speaking, this would be am ancient heresy called modalism, which teaches that God exists as one God, but sometimes He manifests Himself as the Father, sometimes as the Son, and sometimes as the Holy Spirit. This is not to say that the average Christian who explains the Trinity this way is guilty of heresy. More than likely they’re just guilty of an erroneous understanding of the Trinity.
What I’m trying to say is given that we each progress in the Christian faith at different rates, it’s hard to determine if someone is guilty of heresy or simply misinformed. However, if someone persists in error to the point of teaching the error and calling the truth heresy, then you have someone who has ventured outside the Christian faith. This is precisely what has happened throughout church history. The first 400 years of church history was marked by several theological debates that ended up being resolved by church councils. The first major theological debate was over the teaching of a man named Arius who taught that Jesus wasn’t divine, but rather He was just the highest created being. When this teaching started becoming popular, others in the church (in particular a bishop named Athanasius) said this was serious error. The council of Nicaea ( AD 325) was convened and the Arian heresy was condemned. In the Bible, we see something similar happening. There were some who were denying that Jesus came “in the flesh.” The Apostle John wrote, “For many deceivers have gone out into the world, those who do not confess the coming of Jesus Christ in the flesh. Such a one is the deceiver and the antichrist” (2 John 1:7).
So to wrap this up, if you want to know what one has to believe to be a Christian (beyond the basic truth “believe in the Lord Jesus and you will be saved), I would look to the ancient creeds and confessions of the church. We would be fools to ignore the rich history and tradition of our Christian forefathers. The ancient creeds (Apostles’, Nicene, Athanasian) are widely accepted by all orthodox Christians as faithful summaries of the Christian faith. In addition to the creeds, I would add the confessions that arose out of the Protestant Reformation. In the continental reformed tradition, those would be the Three Forms of Unity (Belgic Confession, Heidelberg Catechism, and Canons of Dort). For the English reformed those would be either the Westminster Confession (for Presbyterians), the Savoy Declaration (for Congregationalists), or the London Baptist Confession (for Baptists).
I hope this helps!
~ Pastor Carl
