The Reformers…believed the truth of Scripture could be ascertained, by the help of the Holy Spirit, from the Scriptures themselves. This is what they meant when they said the Scriptures were self-authenticating. Such a reality should come as no surprise. After all Jesus said, “My sheep hear my voice, and I know them, and they follow me” (John 10:27).
It probably comes as no surprise that the most common question I receive from both Christians and non-Christians is “How do I know the Bible is the Word of God?” And the reason this question is at the top of the list is not hard to determine. The authority of the Bible is the foundation for everything that we believe as Christians. It is the source of our doctrine and our ethics. Thus, we need to be able to answer this question when asked.
Let me say from the outset that there is not just one answer to this question. I think there are many ways that Christians can come to know the Scriptures are from God. God can certainly use historical evidences to convince us of the truth of his Word (though it is important to understand the limitations of evidence). And God can use the testimony of the church to convince us of the truth of his Word (I cover the details of this in my book Canon Revisited).
But, it is noteworthy that throughout the history of the church many Christians have ascertained the divine origins of the Bible in yet another way: they read it. Rather than being persuaded through a deep dive into the historical evidences, many have come to believe the Bible is from God by observing its distinctive character and power.