Did the New Testament writers know that they were writing sacred Scriptures?

In chapter 3 page 77 of his book "Did Jesus Exist" Bart Ehrman writes- " The reality is that the authors of the books that became the Bible did not know they were producing books that would later be considered scripture, and they probably had no intention of producing scripture. The Gospel writers—anonymous Greek-speaking Christians living thirty-five to sixty-five years after the traditional date of Jesus’s death—were simply writing down episodes that they had heard from the life of Jesus. Some of these episodes may be historically accurate, others may not be. But the authors did not write thinking they were providing the sacred scriptures for the Christian tradition. They were simply writing books about Jesus".

Here's what I have to say on this.

To say that the New Testament writers had no idea that they were writing sacred scriptures or inspired writings is completely wrong and it is utterly impossible to imagine that Bart Ehrman who is a Distinguished Professor of the New Testament Studies can say something like this. 

Let's look at some of the verses and see what  the New Testament writers thought about their writings.

1. In 1 Corinthians 7:12 To the rest I say this (I not the LORD).

Here Paul is making a clear distinction between what he as Paul writing and what he is writing under the inspiration of God. The fact that Paul made that distinction clearly tells us that Paul knew his writings were considered sacred and inspired.

2. 1 Timothy 5:18 For Scripture says, “Do not muzzle an ox while it is treading out the grain," and “The worker deserves his wages.” now the first portion of this verse comes from Deuteronomy 25:4 Do not muzzle an ox while it is treading out the grain  however the second portion of the verse which says "The worker deserves his wages" is nowhere found in the Torah and Prophets, it is found in the Gospel according to Luke chapter 10 verse 7 which means Paul the writer of First Timothy considered Luke's writing at par with the Torah for Paul says "For Scripture says". He's referring to Luke's writing as Scripture.

3. 2 Peter 3:15,16 Bear in mind that our Lord’s patience means salvation, just as our dear brother Paul also wrote you with the wisdom that God gave him. He writes the same way in all his letters, speaking in them of these matters. His letters contain some things that are hard to understand, which ignorant and unstable people distort, as they do the other Scriptures, to their own destruction.

Here Peter referred to Paul's writings as Scriptures.

4. 1 Corinthians 14:37,38: If anyone thinks they are a prophet or otherwise gifted by the Spirit, let them acknowledge that what I am writing to you is the Lord’s command. 38 But if anyone ignores this, they will themselves be ignored. Here Paul directly says that whatever he is writing is inspired and a command from God, this is no less than Scripture.

5. 1 Thessalonians 2:13 And we also thank God continually because, when you received the word of God, which you heard from us, you accepted it not as a human word, but as it actually is, the word of God, which is indeed at work in you who believe. Here Paul directly tells his Church in Thessaloniki that his word is indeed God's word.

I gave just 5 verses to establish that the New Testament writers were fully aware that they were writing the inspired Scripture.