When people ask me why I believe the Bible is the inspired word of God, I answer very differently than the average evangelical, although I share the same doctrines.
The first thing I became convinced of was the truth of the spoken gospel itself. I had heard the gospel before. I understood the theological statements in it. I comprehended the claims it was making. But one day it suddenly became real for me. All at once it seemed absolutely and irrevocably obvious that I was a sinner in need of forgiveness, that Jesus had died for my sins, that he was alive and calling me into relationship with him, and that the very illumination I was suddenly experiencing was the work of the Spirit of Jesus himself, showing it to me.
Second, I noticed than when I read the Bible, portions of it came alive in the same way. I had heard God speaking to me in the gospel; now I heard him speaking to me as I read the Bible. The transcendent intensity of this experience of “being spoken to” drew me back again and again. Sometimes I felt it when I read the Bible; other times I did not.
Third, I began to pay attention to what the Bible said about itself, and about this experience. The key concept was the “word of God”. Sometimes this referred to the spoken gospel, sometimes to the written Scriptures. Always, it was spoken of as having the power to penetrate to our hearts and convince us of its truth.
For example, these verses to the Thessalonians could easily be describing my own experience:
… our gospel did not come to you in word only, but also in power and in the Holy Spirit and with full conviction … 1 Thess 1:5
For this reason we also constantly thank God that when you received the word of God which you heard from us, you accepted it not as the word of men, but for what it really is, the word of God, which also performs its work in you who believe. 1 Thess 2:13
Note what Paul did not say here: he didn’t say, “Good for you, for accepting our word as true”. He said, “Thank God that his word performed its work in you”.
Similarly in Rom 10:13 Paul said
So faith comes from hearing, and hearing by the word of Christ.
By hearing, here, he means really hearing, i.e., the sharp burst of illumination in which you suddenly really get that it is true, and he says it is the gospel itself that brings that illumination and inspires faith.
Speaking of the written and spoken word of God both, Paul said:
Now we have received, not the spirit of the world, but the Spirit who is from God, so that we may know the things freely given to us by God … but a natural man does not accept the things of the Spirit of God, for they are foolishness to him; and he cannot understand them, because they are spiritually appraised. 1 Cor 2:12-14
What does this mean? Obviously there are many intelligent people who are not believers who are able to understand the theological statements made in the Scripture. Paul’s point is that without the Holy Spirit they do not appraise them correctly. That is, they comprehend the meaning but are unable to see that they are true.
The author of Hebrews says:
For the word of God is living and active and sharper than any two-edged sword, and piercing as far as the division of soul and spirit, of both joints and marrow, and able to judge the thoughts and intentions of the heart. Heb 4:12
This described very accurately what was happening to me when I read the Bible sometimes.
In this context, 2 Tim 3:14-16 is very relevant.
You, however, continue in the things you have learned and become convinced of, knowing from whom you have learned them, and that from childhood you have known the sacred writings which are able to give you the wisdom that leads to salvation through faith which is in Christ Jesus. All Scripture is inspired by God and profitable for teaching, for reproof, for correction, for training in righteousness; so that the man of God may be adequate, equipped for every good work
In other words, all of the Scriptures, not merely the parts that have spoken to me thus far, have the capacity to speak to me.
That last set of verses is very important because it shifts the focus from my own experience of God speaking to me to the objective words of the Bible itself. God got my attention and convinced me the Bible was His word through the felt conviction of the Holy Spirit; in the future, I can believe that this is so even without that felt conviction.
Now, I understand perfectly well that to someone who is unsure whether the Scripture itself is inspired, none of the verses above can prove that it is – that would be circular logic. But to one who already keeps hearing God speak to him in the Bible, these verses explain what is happening and why.
Finally, I was taught the technical details of the doctrine of the inspiration of the Scriptures. That doctrine is important. At its best, it summarizes and synthesizes all the many things that the Bible says about itself and the Christian experience and understanding of those statements across history; it unwraps the complex implications of those statements; and it guards against heresies that have sprung up from age to age. In my case, though, I was’t taught much about the Bible’s inspiration until after I was already reading, believing, and obeying it the best I could.
Here’s my primary point: sometimes we evangelicals are say, “It’s important that people believe the Bible. If they aren’t willing to believe the Bible, how will they believe the gospel?” I think that gets things backwards. Most of the time, people believe the gospel first and the Bible afterwards.