2Timothy 3 comes to mind.
The whole chapter.
Especially vs 16.
Now Paul at this point is talking about the Old Testament...he really didn't think that he was writing over a third of the New Testament.
As scripture is obviously written by men it really is a wonder how ordinary men were inspired by God.
And it's an important part of why scripture is scripture. I'd even go so far as to say that certain hymns that are known today are "God Breathed". Amazing Grace is one of those.
It has to do with holy truth and the Holy Spirit.
John,
We are told how ordinary people could write God-breathed Scripture:
16 For we did not follow cleverly devised stories when we told you about the coming of our Lord Jesus Christ in power, but we were eye-witnesses of his majesty. 17 He received honour and glory from God the Father when the voice came to him from the Majestic Glory, saying, ‘This is my Son, whom I love; with him I am well pleased.’ 18 We ourselves heard this voice that came from heaven when we were with him on the sacred mountain.
19 We also have the prophetic message as something completely reliable, and you will do well to pay attention to it, as to a light shining in a dark place, until the day dawns and the morning star rises in your hearts. 20 Above all, you must understand that no prophecy of Scripture came about by the prophet’s own interpretation of things. 21 For prophecy never had its origin in the human will, but prophets, though human, spoke from God as they were carried along by the Holy Spirit (2 Peter 1:16-21 NIV).
It happened because of the work of the Holy Spirit in causing frail human beings to write prophetic Scriptures. The origin is the Holy Spirit but the means is through people.
That relates to the mystery of the ministry of the Holy Spirit. I don't expect unbelievers or doubters to understand or accept it. I'm not being naive but accepting God, based on what he has told us.
There is potential for typos (called variants) with hand copying but that doesn't affect the God-breathed nature of the originals.
Oz