"Men and brethren, this Scripture had to be fulfilled, which the Holy Spirit spoke before by the mouth of David concerning Judas, who became a guide to those who arrested Jesus; for he was numbered with us and obtained a part in this ministry."
Acts 1:16-17

How did the Holy Spirit inspire the scriptures?

The scriptures, not merely the writers, are indeed inspired (“God breathed”) (2 Timothy 3:16-17). This means the scriptures are the very words of God (He is the “Author”). How did He do this seeing that we can detect differences between the human “writers” (not “authors”) of the Bible?

Some say God inspired the human authors (maybe planting ideas in their heads), and they subsequently wrote what they thought. That would mean the words of scripture are their words, not God’s. This cannot be so.

Others say that God “dictated” the scriptures and that the human writers sort of “channeled” God. This is not so because, again, the humanity of the human writers is evident in what they wrote.

The third option is that God supernaturally superintended over the human writers in such a way that they wrote the very words God wanted written, while the Lord allowed the personalities of the human writers to be seen. This option is correct.

What difference does this make? Our Bibles are the very words of God, so we trust them to be inerrant, and therefore completely authoritative. We may not pick and choose which passages we agree with and discard the rest.

All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness, that the man of God may be complete, thoroughly equipped for every good work. (2 Timothy 3:16-17)