The Internal Testimony of the Holy Spirit: How Do You Know That the Bible Is God’s Word?


James N. Anderson

Article ID:



Sep 27, 2023


Nov 12, 2017

This article first appeared in the CHRISTIAN RESEARCH JOURNAL, volume 39, number 05 (2016). The full text of this article in PDF format can be obtained by clicking here. For further information about the CHRISTIAN RESEARCH JOURNAL click here.


If you’re a regular reader of the Christian Research Journal, I suspect that question immediately prompts you to think of arguments and evidences for the divine inspiration of the Bible. Take, for example, the fulfilled biblical prophecies, the astonishing consistency and unity of the Bible’s message despite having many human authors over hundreds of years, and the testimony of Jesus, who confirmed His claim to be the Son of God by His resurrection from the dead.

Those would be good thoughts, but there’s a problem with answering the question in that way. If a Christian’s knowledge that the Bible is God’s Word depends on being able to marshal various arguments and evidences, then surely only a small minority of Christians actually know that the Bible is God’s Word. The majority of Christians may believe it, but they don’t know it, simply because they’re not familiar with these apologetic evidences. They’ve never been asked to justify their beliefs in that way, and they wouldn’t know how to do it if they were asked.

Obviously it would be very unfortunate if it turned out that most Christians don’t actually know that Christianity is true. It also seems quite implausible. Take my late grandmother, for example. Her Christian faith towered over mine. Should I conclude that I knew something she didn’t — namely, that the Bible she built her life on is indeed God’s Word — because she wasn’t able to marshal arguments and evidences in the way that I can?

To think that would be not only implausible but also elitist. It would imply that only those Christian believers who attain to a certain level of intellectual sophistication can enjoy knowledge of the divine inspiration of the Bible. Yet that would be quite at odds with the practice of Jesus and the apostles, who routinely appealed to Scripture on the assumption that their audience knew that Scripture was divinely authored and therefore divinely authoritative.

Fortunately, we don’t need to set such a high bar for knowledge of basic Christian truths. There’s a more generous view — indeed, a more gracious view — that has been the mainstream perspective among Protestants since the Reformation. A classic formulation can be found in the first chapter of the Westminster Confession of Faith:

  1. The authority of the Holy Scripture, for which it ought to be believed, and obeyed, dependeth not upon the testimony of any man, or church; but wholly upon God (who is truth itself) the author thereof: and therefore it is to be received, because it is the Word of God.
  1. We may be moved and induced by the testimony of the church to an high and reverent esteem of the Holy Scripture. And the heavenliness of the matter, the efficacy of the doctrine, the majesty of the style, the consent of all the parts, the scope of the whole (which is, to give all glory to God), the full discovery it makes of the only way of man’s salvation, the many other incomparable excellencies, and the entire perfection thereof, are arguments whereby it doth abundantly evidence itself to be the Word of God: yet notwithstanding, our full persuasion and assurance of the infallible truth and divine authority thereof, is from the inward work of the Holy Spirit bearing witness by and with the Word in our hearts.

Note four things asserted here. First, the Confession states that the Bible is the Word of God simply because it is authored by God, and therefore it has intrinsic authority regardless of what anyone says or thinks about it. Scripture is God’s Word as a matter of objective historical fact.

Second, the Confession says that the Christian church has an important role to play in people coming to believe that the Bible is God’s Word. The church bears witness to the divine inspiration of Scripture, and that counts for something, even if it’s not sufficient in itself to establish that the Bible is God’s Word.

Third, the Confession acknowledges that Scripture exhibits all the marks of a divine revelation. It possesses “many incomparable excellencies” that are evidences of its divine authorship. Again, these are objective facts about the Bible.

Finally, the Confession asserts that in order to have an assured knowledge that the Bible is God’s Word, there must also be what Reformed theologians have called the internal testimony of the Holy Spirit (ITHS): an “inward work” of the third person of the Trinity in the heart and mind of a believer, bringing about a kind of direct apprehension that the Bible is God’s Word. 


One of the biblical texts cited in connection with ITHS is John 10:27, where Jesus says, “My sheep hear my voice.” According to Jesus, the reason His Jewish critics didn’t believe His claims was because they were “not among my sheep” (v. 26). What then defines Jesus’ sheep? They hear His voice. Jesus is referring here to a spiritual apprehension rather than a mere physical reception of His words. The sheep are those who recognize the voice of the Shepherd. As they hear His voice, they know His true identity. But this knowledge cannot come through merely natural means.1

An analogy may help here. I imagine most readers have had the experience of receiving a phone call where the caller’s opening words are simply, “Hey, it’s me!” Even though those words could be said by anyone, I’d wager that nearly every time you’ve receive an “It’s me!” call, you knew immediately and certainly who the caller was. But how did you know, since the speaker didn’t give a name? It’s simple: you recognized the person’s voice. You didn’t engage in some process of deduction from various “evidences” that you identified in their speech. You directly perceived the identity of the caller.

Something analogous takes place when the Spirit bears witness to Scripture. The Bible bears all the objective marks of a divine revelation, but we nevertheless need “eyes and ears” to recognize it as such. That spiritual apprehension is one of the gifts of the Holy Spirit. When we read or hear the words of the Bible, the indwelling Spirit brings about in our hearts and minds a conviction that these aren’t merely human writings. In short, the Spirit of God enables us to hear the voice of God speaking in the Word of God.

This account of how we know that the Bible is God’s Word has a number of theological virtues. I’ll mention just two here. First, it honors the doctrine of salvation by grace alone. Our knowledge of the great truths of the gospel, which are revealed in the Bible and by which we are saved, doesn’t rest on our own intellectual abilities or efforts. ITHS puts all believers on an equal footing. Anyone, regardless of their level of intellect or education, can know that the Bible is God’s Word. Saving knowledge of God is a supernatural divine gift, not a natural human achievement.

Second, this account comports with the Protestant conviction that the Bible is a self-attesting revelation. We don’t accept its authority on the basis of some other authority (the Pope, theologians, scientists, historians, etc.) but because God Himself testifies to it. Since the Bible is God’s Word, it has the highest possible authority; no one other than God is in a position to testify to its authority (cf. Heb. 6:13). Thus it’s only appropriate that our faith in the Bible is secured by the internal testimony of God’s Spirit.


The Reformed view has theological attractions. But is it philosophically credible? One of the most sophisticated defenses of ITHS has been developed by Alvin Plantinga.2 In a trilogy of books known as the Warrant series, Plantinga analyzed the necessary conditions for human knowledge. He concluded that a person S knows some proposition P only if:

(1) S believes P;

(2) P is true;

(3) S’s belief in P is produced by a cognitive faculty that is (a) functioning properly in an appropriate environment and (b) successfully aimed at truth.3

Plantinga describes how this account can explain various kinds of knowledge we take for granted: sense perception, knowledge of the past, knowledge of basic moral truths, knowledge of abstract truths about logic and mathematics, even knowledge of the existence and attributes of God. (The last of these he attributes to a sensus divinitatis: a cognitive faculty that produces what theologians call “the natural knowledge of God.”)

When it comes to knowing that the Bible is God’s Word, however, Plantinga recognizes that we possess no natural faculty that could deliver such knowledge. Nevertheless, ITHS can be seen as analogous to our natural cognitive faculties in a way that meets all of the necessary conditions for knowledge. If P is the proposition that the Bible is God’s Word, and S is someone in whom the Holy Spirit has brought about a recognition that P is true, we can say that S knows P because (1) S believes P, (2) P is true, and (3) S’s belief in P is produced by a kind of cognitive process — albeit a supernaturally enhanced one — that is successfully aimed at truth. Plantinga’s is certainly not the only philosophical explication of the Reformed position, but it is the one that has been most rigorously developed and defended.


In this last section, I want to address briefly three concerns the reader might have with the view I’ve sketched. The first concern is that ITHS would be intrinsically subjective, which in turn implies a subjectivist view of knowledge. Admittedly there is a subjective aspect to ITHS, since the Holy Spirit operates on the subject of knowledge internally and does so on an individual (and selective) basis. In reality, however, there is a subjective aspect to every type of knowledge. Consider my knowledge that I had cereal for breakfast. That’s subjective in the sense that it’s my memory that supplies this knowledge, and I’m the only person who has direct access to memories of my past experiences. Does that imply subjectivism about knowledge? Not in any objectionable sense.

Another concern is that ITHS is no more respectable than the Mormon doctrine of the “burning bosom,” and thus anyone who holds the Reformed view must forfeit the right to criticize the Mormon view. According to the Mormon teaching, if you want to know whether the Book of Mormon is true, you should pray to God about it, and if it is indeed true, God will “cause that your bosom shall burn within you; therefore, you shall feel that it is right.”4 This experience is taken to confirm the divine origins of the book.

We should note, however, several crucial differences between ITHS and the Mormon view:

  1. ITHS doesn’t involve any fleece-laying test, as the Mormon practice does. The internal witness of the Spirit is entirely a divine initiative.
  1. ITHS doesn’t involve any inference from a subjective feeling. The Christian’s knowledge that the Bible is God’s Word may be accompanied by a kind of cognitive experience, but it isn’t based on a deduction from any such experience. “I feel that the Bible is true, therefore it is true,” would be a gross distortion of the Reformed view.
  1. ITHS doesn’t operate independently of objective evidences for the divine authorship of the Bible. Rather, it involves a Spirit-enabled apprehension of those evidences. In contrast, the Mormon teaching suggests that one can come to know that some book is from God regardless of whether there is any publicly examinable evidence. In effect, the “burning bosom” test tries to do an end-run around the issue of objective evidence.

A third concern is that ITHS would make apologetics redundant. If someone can know that the Bible is God’s Word without relying on arguments and evidences, doesn’t that put Christian apologists out of a job? Not at all. In the first place, we should distinguish between knowing and showing.5 I can know that the Bible is God’s Word without arguments and evidences, but if unbelievers ask me why they should believe that, it won’t do to reply simply, “The Holy Spirit bears witness in my heart!” In order to show others that it’s true, I need to provide them with reasons to believe it. I need to engage in apologetics, which the Holy Spirit may be pleased to use to bring those unbelievers to Christian faith.

Moreover, while apologetics may not be necessary for an initial knowledge of the divine authorship of Scripture, it may be necessary to nourish and protect that knowledge. Christians today increasingly are confronted with intellectual attacks on the Bible, which give rise to doubts. Christian apologetics is one of the God-given means of resolving those doubts.

So there’s no necessary conflict between ITHS and Christian apologetics. ITHS ensures that every Christian can know the truth about the Bible, while apologetics equips Christians to defend and demonstrate that truth.


James N. Anderson, PhD, is associate professor of theology and philosophy at Reformed Theological Seminary in Charlotte, North Carolina, and a minister in the Associate Reformed Presbyterian Church.


  1. Compare Jesus’ response to Peter’s testimony in Matthew 16:16–17.
  2. Plantinga’s views are associated with the broader movement known as Reformed epistemology.
  3. For Plantinga’s own summary, see Warranted Christian Belief (Oxford: Oxford University Press, 2000), 153–56.
  4. Doctrine and Covenants 9:8–9.
  5. See, e.g., William Lane Craig, Reasonable Faith, 3rd ed. (Wheaton, IL: Crossway, 2008), 43–58.


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