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What Must a Christian Believe?


Imagine that you’re in London. The year is 1675; it’s been fewer than ten years since the Great Fire ravished the city. One Sunday afternoon, after lunch, you walk down Bishopsgate Street to discover a constant flow of people entering the great hall of the Crosby House. The large home’s owner is Sir John Langham, a Nonconformist who has left the Church of England.

Intrigued, you join the crowd and find that they’ve gathered to learn the basics of the Christian faith. Thomas Watson and Stephen Charnock, two pastors concerned that their congregation will be grounded in Christian doctrine, lead the instruction. (Watson and Charnock would lead their churches’ members through a series of questions and answers that they referred to as “a body of divinity”—the information necessary to understand God.)

As you sit among the eager students that Sunday afternoon, Watson informs those present of his purpose:

To preach and not to catechise is to build without foundation. … It is my design, therefore (with the blessing of God), to begin this work of catechising the next Sabbath day; and I intend every other Sabbath, in the afternoon, to make it my whole work to lay down the grounds and fundamentals of religion in a catechistical way. If I am hindered in this work by men, or taken away by death, I hope God will raise up some other labourer in the vineyard among you, that may perfect the work which I am now beginning.1

It was the conviction of Watson and Charnock, and others like them, that every Christian is to be settled in the faith. And this settling was and is to come only through being grounded in the truths of God’s Word (Eph. 4:11–14).

Knowing What and Why We Believe

This example from history illustrates a timeless principle: Christians must know what they believe and why they believe it. Indeed, this emphasis on doctrinal belief is at the very heart of apostolic preaching. It’s a prominent theme in the New Testament. Writing to the Colossians, Paul says,

You, who were once alienated and hostile in mind, doing evil deeds, he has now reconciled in his body of flesh by his death, in order to present you holy and blameless and above reproach before him, if indeed you continue in the faith, stable and steadfast, not shifting from the hope of the gospel that you heard. (Col. 1:21–23)

How is a congregation to hold onto the Gospel when the world wages war against it? The answer is in verse 23: by remaining “stable and steadfast,” not “shifting” from Gospel truth. When we are settled in what we believe, being grounded in truth gleaned from personal study, pastoral instruction, and the Spirit’s application, we may then stand firm.

Knowing what we believe doesn’t mean becoming a scholar in every theological discipline. Rather, the Bible’s focus is on mastering the main things, the basics of the Christian faith (Rom. 16:17; 2 Tim. 3:14; 1 John 2:24). Just as disciplines like art, economics, or mathematics have a set of first principles upon which they’re built, so Christianity has certain foundational doctrines.

Theology has little to do with intellectual capacity.

When it comes to Christian belief, our task and privilege, individually and collectively, is to understand the first principles of our faith, bringing them to bear on every aspect of our lives.

The Core Christian Beliefs

The key affirmations of the Christian faith all have to do with the being of God. They deal with eternal truths. And rightly receiving these truths requires dependence and obedience.

First, we learn doctrine as dependent men and women. We’re finite creatures, unable to comprehend the infinite God without His help. In this sense, there’s no intellectual route to God. Only when He is pleased to take the initiative in revelation may we know what it is we believe and why we believe it.

Second, we must acknowledge that obedience, not intellect, is the key to learning Christian doctrine. In fact, contrary to most disciplines, theology has little to do with intellectual capacity . It’s about faithfully living out the truth as it comes to us.

God’s Spirit confirms to us the truthfulness of the Bible’s teachings.

With this context in mind, what must a Christian believe? While this list could be debated, deserves more nuance, and is understood to varying degrees by equally faithful believers, we can at least begin with these ten essentials of the faith:

  1. the oneness, or unity, of the Father, Son, and Holy Spirit in the Godhead
  2. the sovereignty of God in creation, revelation, redemption, and final judgment
  3. the divine inspiration of Scripture; its infallibility as originally given; its sole authority and complete sufficiency in all matters of faith and conduct
  4. the universal sinfulness and guilt of human nature since the fall, rendering men and women subject to God’s wrath
  5. redemption from the guilt, penalty, and power of sin only through the sacrificial death of our representative and substitute, Jesus Christ, the incarnate Son of God
  6. the physical resurrection of Jesus from the dead
  7. the necessity of the Holy Spirit’s work to make Jesus’ death effective to the individual sinner, granting him or her repentance toward God and faith in Jesus Christ
  8. the indwelling work of the Holy Spirit in the believer
  9. the one holy, universal church, which is the body of Christ and to which all true believers belong
  10. the expectation of the personal return of the Lord Jesus Christ in power and in glory

This list represents the “main and plain” doctrines of the Bible. It is the work of God’s Spirit to confirm for us the truthfulness of these things and the veracity of the source for these things—namely, His Word.

A Clear and Present Danger

In response to the need for a clearly defined set of beliefs, someone may ask, “Why must we be so dogmatic about doctrine? Does it ultimately matter what a person believes?” The assumption underlying this idea is that Christians can get along just fine without any defined beliefs. But from the New Testament through church history and into the modern day, the fact is that settled beliefs on the main things help to preserve the church’s purity and witness.

Another person says, “Alright, we won’t dismiss theology, but how about we adapt some core beliefs to fit better with the modern world?” The answer must be no, for the message we preach centers on a crucified Savior for whom we should be willing to give up everything to follow (1 Cor. 1:22–24; Luke 14:25–27). The Gospel is contrary to what the world values.

The lack of defined beliefs is a clear and present danger—yet such a temptation is alive and well! But it matters what a Christian believes. For the sake of the Gospel and for the faith of the next generation, we must be settled in the basics—grounded in the soil of God’s Word.


This article was adapted from the sermon “Believing” by Alistair Begg. Download or purchase The Basics of the Christian Faith: A 13-Lesson Survey.


  1. Thomas Watson, A Body of Divinity (Edinburgh: Banner of Truth, 1965), 5. ↩︎

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