The Bible is God-breathed and perfectly true for a number of reasons:

1. Historical and cultural accuracy. The Bible is true because it has been shown to be true.
2. The Bible is true because it speaks truthfully to the human condition. It speaks of the reality of human nobility and cruelty, of temptation and strength, of courage and fear.
3. The Bible is true because it speaks truthfully about the natural world. It speaks of the wonderful glory of nature but also its danger, of its beauty and design but also its brokenness.
4. The Bible is true because it speaks truthfully about God. Billions of people through history affirm that what the Bible says about God they have experienced in their own lives and can confirm the truth of it.
5. And finally, the Bible is also true because it says so. When we see the veracity of the Scriptures through every other facet of life, we also recognize it as true when it tells us, "By the way, God is the source of this information."

All of the Bible is God-breathed (2 Tim. 3.16). We are able to (and are commanded to) trust the entire Bible as perfect truth (Mt. 5.18-19).
So the Bible is God-breathed and perfectly true because the Bible says so? I genuinely don’t understand how this is supposed to work.

It's difficult to separate that out. It's likely that Paul was speaking about the Tanakh (all of the Scriptures [what Christians call the Old Testament], not just the Torah). On the other hand, though, and for further consideration, the term Paul uses (πᾶσα) means *every* passage of Scripture, and stems from verse 15: "Everything that has been recognized as authoritative Scripture"—"which are able to make you wise for salvation through faith in Christ Jesus." It seems that he intends to include more than the Tanakh. In 2 Peter 3.16, the author puts Paul's writings on the same plane and in the same category of "Scripture." And there is no doubt that the apostles claimed to be writing by help of the Holy Spirit, just as the prophets did. The early recognition and circulation of Paul's letters as authoritative contributes to our understanding that the Church recognized them as Scripture from the very beginning. 1 Corinthians 14.37-38 also point in this direction. Paul quotes the Gospel of Luke (10.7) in 1 Tim. 5.18 and calls it "Scripture."

The term used for "Scripture" (γραφὴ—a common term) used in 2 Tim. 3.16 is often used of the Tanakh—the OT. But here it is without the article, and therefore it is more general not only of the scriptures as a whole, but of each separate passage. Paul is allowing a broader understanding (without specifying what that scope is).

When Paul wrote 2 Timothy in the 60s, many of his books had already been written (2 Tim. was fairly late in the sequence). Some feel, as I do, that several of the Gospels were newly written (particularly Mark and Luke)—and both Mark and Luke were traveling companions of Paul. (I put 2 Timothy fairly early compared to some other scholars; I put it at 62-64. I also put 2 Peter in the early 60s.)

We are left to interpret his words in 2 Tim. 3.16. I think there is enough credibility in the textual evidence to show us that Paul was definitely talking about the Tanakh and probably including the Gospels and his own writings as extended categories of the term "scripture."

Is it your opinion that Paul was stating in a letter to Timothy that his letter to Timothy was God-breathed? Or is it possible that Paul was referring to the Torah, since the New Testament Bible did not exist when he wrote that letter?

This is an excellent question. I’m going to give you a nuanced answer.

First of all, there are two things we know for sure:

1. We are saved because we have the nature of Jesus in us, by grace through faith. Our view of Scripture is never ever portrayed in the Bible as one of the conditions for salvation. Our salvation is based on the blood of Christ alone, and we respond to his invitation to receive him (Jn. 1.12). There is no indication in the Bible that, for instance, a view of Gn. 1 as metaphor rather than history, a view of Job or Jonah as fiction, will keep one out of heaven. History tells us, for example, that Martin Luther claimed that book of James was "an epistle of straw," and he was greatly displeased with its inclusion in the New Testament.

2. All of the Bible is God-breathed (2 Tim. 3.16). We are able to (and are commanded to) trust the entire Bible as perfect truth (Mt. 5.18-19). We are given no warrant as followers of God to exclude even a single letter.

With these two irrefutable facts in front of us, where do we go, then, with your question? It’s not black-and-white, but instead nuanced. I will say it this way: all of the Bible is perfect truth, and we are expected to trust it as God-breathed and beneficial for teaching, rebuking, correcting, and training in righteousness (2 Tim. 3.16). But we also know this, just as clearly: when people first come to Christ, they often have an incomplete understanding of Christ and Christianity, and God needs to shape them, guide them into all truth (Jn. 16.13), and sanctify them (Jn. 17.17). I would venture a guess that all of us have, somewhere in us, misunderstandings about God and His Word that God is gradually and progressively teaching us.

In other words, if a young Christian doesn’t believe all of the Bible, I think he/she is still a Christian, and in the course of time God will convince that individual of the inspiration of ALL of Scripture. It is expected that all of us buy into ALL of Scripture. But suppose that person never comes to that point? I don’t think they lose their salvation. Salvation is never predicated on our view of Scripture. But I would say that person is going to have an inadequate view of God, I would include a wrong view of Scripture, and their deprecatory view of the inspiration of ALL of Scripture will have a detrimental effect on their Christianity and on any with whom they speak. But are they not saved? I would never say that. Lots of Christians are still saved even though they give in to temptation, indulge in various sins, have a distorted view of God or Scripture, or don’t in some way subscribe to the whole “Christianity” package. Salvation is never conditioned by being 100% orthodox (that unless you have it all you have nothing).

So you see why I would call my response “nuanced.” The ideal that is expected is not the only possibility. God in His grace allows us to hold less-than-satisfying positions without jeopardizing our salvation.

Feel free to respond, disagree, or ask more questions.

How much of the Bible do I actually have to believe to be considered a Christian?

The common view I've been seeing as of recent is that you don't have to believe in the following:

A literal Adam and Eve
Noah and the flood
Moses and the Exodus story
The witch of Endor
Legends surrounding King David.
Most of the Old Testament really

Alternatively, I hear that Christianity "lives and dies by the resurrection", but to what extent does the resurrection live or die by the events above?