Beliefs make Christianity, but the relationship makes the Christian.
What does it mean to be a Christian? For many people, it seems to mean that you believe certain things. I often hear the idea implied that the gospel is about holding a certain set of beliefs. While it is true that being a Christian means believing certain things, that is not all there is to it. To be a Christian implies that you have a relationship which entails certain beliefs.
By "beliefs", I mean propositions which you affirm. "Do you believe that Jesus died on the cross for your sins?" "Do you believe that Jesus rose from the dead?" Do you believe that Jesus is coming back?" Do you believe that only those who trust in Jesus for forgiveness of their sins will have eternal life with God?"
It is a simple observation that you may affirm all these things with a "yes" and still not be a Christian. That is because the link between those propositions and your life is absent. One only needs to add the question, "Have you called on God for salvation and trusted in him for the forgiveness of your sins?" The answer to that question demands an affirmation not only of certain beliefs, but of a certain relationship.
Please do not misunderstand me: believing the right things is essential. You cannot know God if you believe the wrong things about him. You cannot be saved if you do not believe that Christ died on the cross for our sins, that he rose again, and that it is through this sacrifice that our sins can be forgiven. These and others are essential beliefs. However, affirming right doctrine no more makes you a Christian than affirming planes can fly makes you a pilot.
To be a Christian means to be reconciled to God, to have peace with God through the Lord Jesus Christ. That peace and reconciliation entail certain beliefs, but those beliefs do not constitute the relationship. The relationship is what makes the Christian; the beliefs describe and delimit it.
Therefore, to know the gospel and be reconciled to God are not the same thing. You can know the gospel without being reconciled God, but you can’t be reconciled without knowing the gospel. Affirming a set of propositions is no substitute for worshipping in spirit and in truth.
And yet, this is precisely the crack in thinking into which many people fall. There is often a lack of an existential grasp of what it means to be a Christian. People affirm they are believers and yet have no relationship with God to speak of.
And perhaps that’s one reason the term “believer” should not be the only one we use to refer to Christians. Scripture uses "saint", "child of God", "servant/slave of Christ", "household member", "sheep", "follower", etc. All of these terms require much more than mental assent to ring true for us. If we expanded our list of terms beyond "believer", this could be a little more clear, and the crack could be narrowed.
When someone calls himself a Christian but only means “I affirm the core teachings of Christianity”, there ought to be a cognitive dissonance in our minds. It should just be weird. What good is belief in Christ without devotion to him? What use is affirming the resurrection without living for it? Why assent to Jesus’ lordship without obeying him?
The core of Christianity is a right relationship with God through Jesus Christ. The relationship entails certain beliefs which are absolutely essential. But the beliefs are no substitute for the relationship, and that is precisely the mistake so many seem to make.
Many seem to think affirming the right propositions is sufficient basis for claiming to be Christian. But even demons can do that. Unbelievers who are dead in sin are capable of affirming true things about God. But that does not make them alive to God.
Instead, we must understand that being a Christian entails having certain beliefs and affirming certain propositions, but having those beliefs and affirming those propositions does not make you a Christian. The substance of Christianity is a right relationship with God. You cannot have the relationship without the right beliefs, but you can have the right beliefs without the relationship. You can know what is right without submitting to God. You can know God is sovereign and still rebel. You can know the sacrifice and resurrection of Christ without having forgiveness.
This is not a minor issue. Eternal destinies are at stake. When people mistake beliefs for relationship, souls are consigned to Hell.
This is why I began by saying that beliefs make Christianity, but the relationship makes the Christian. This is to say that Christianity understood as a worldview is identifiable by its distinguishing beliefs and propositions which it affirms. When we compare worldviews, we are dealing in the exchange of ideas and how one set of ideas compares and contrasts with another. Christianity has its own set of ideas, as does Islam, Hinduism, Agnosticism, etc. And we derive, or ought to derive, the right set of ideas about Christianity from the Bible, which is God's revealing of innumerable right ideas, and which serves as the basis for our own.
So ideas are nothing to be sniffed at. Doctrines, catechisms, creeds, confessions, and statements cannot be skipped or deemphasized. The key idea in this article is to make the point that the ideas about Christianity contained in Scripture help us to understand that right ideas are essential but not sufficient. Having the right ideas about God, the world, mankind, and the future does not make someone a Christian. Having peace with God through Christ makes someone a Christian. Being foreknown, elect, called, regenerated, justified, converted, and adopted is what makes someone a Christian. And the Christian will be sanctified and glorified.
Imagine a person who has been invited to a party. The person drives through a neighborhood and parks outside the house. It is the right house, on the right street, in the right neighborhood, in the right city, in the right state, in the right country. So many things had to go right for this person to park outside this house. And if anyone asked the person, the person would affirm with total confidence that this is the right house. Now imagine that the person never enters the house and joins the party. What good is knowing the right facts about the party if, once having arrived, you never join?
I fear this experience is all too common. There are more people parked at the right house than have actually joined the party. Christianity is about living for God through Christ. It is not enough to know which God to live for and through whom. This is why beliefs make Christianity, but the relationship makes the Christian.