2 Timothy 3:16 (NKJV)
All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness,
If you argue that the Bible just contains the word of God as opposed to fully being the word of God then you need to decide which parts are and are not. Suddenly man is the editor. This would make the Bible as untrustworthy as man.
The Greek word for inspiration in the above verse means God out-breathed. The Bible is God's word. Paul is not just referring to the Old Testament either when he says "All Scripture."
Let's examine how the writers of the epistles knew they were writing scripture. In the following passage, notice how Peter includes Paul's writings when he speaks of scripture, putting them on the same plane as the Torah, venerated by any Jew including Peter.
2 Peter 3:14-16 (NKJV)
Therefore, beloved, looking forward to these things, be diligent to be found by Him in peace, without spot and blameless; and consider that the longsuffering of our Lord is salvation--as also our beloved brother Paul, according to the wisdom given to him, has written to you, as also in all his epistles, speaking in them of these things, in which are some things hard to understand, which untaught and unstable people twist to their own destruction, as they do also the rest of the Scriptures.
The Apostles recognized that they were writing scripture even as they were writing it!
Paul speaks of scripture and quotes from Deuteronomy and Luke
1 Timothy 5:18 (NKJV)
For the Scripture says, "You shall not muzzle an ox while it treads out the grain," and, "The laborer is worthy of his wages."
Deuteronomy 25:4 (NKJV)
4 "You shall not muzzle an ox while it treads out the grain.
Luke 10:7 (NKJV)
7 And remain in the same house, eating and drinking such things as they give, for the laborer is worthy of his wages. Do not go from house to house.
So you see that Paul is citing Luke's writing alongside Moses again making the Gospel of Luke as authoritative as the Torah.
In the Upper room discourse, Jesus pre-approves the New Testament. Notice what he says:
John 14:26 (NKJV)
But the Helper, the Holy Spirit, whom the Father will send in My name, He will teach you all things, and bring to your remembrance all things that I said to you.
Of course Jesus' words had to be written down. How else would we know of Him? It is the specific task of the Holy Spirit job to inspire these men to complete our Bible.