WHO WROTE THE BIBLE
Was the Bible written by men who were inspired by God or was it written by men who were telling tall tales, motivational stories, or trying to deceive in order to gain something for themselves? Were the authors of the books of the Bible who they claim to be? Because if they were not then we have a problem, how did men who were either delusional or deceptive write a book that, apart from authorship, contains evidences of divine origins? That is, how did writers who were lying or deceived get the details correct? That is one overall evidence that the Bible writers were authentic.

It is not possible to actually confirm that any particular individual wrote a book of the Bible, apart from what the Bible says and what has been passed down from tradition. There are no signatures to compare, no fingerprints, just copies of what they wrote that have been passed down through the centuries.  What we have is archeological evidence and old manuscripts.

So if we can't be sure who wrote the Bible, then how did the critics of the 18th and 19th centuries figure out that five different writers wrote the Pentateuch, or Daniel was written by a 2nd century BC imposter, or Isaiah was actually two or more people?  Without getting technical, they did it by looking at the text and deciding whether it showed consistent enough writing styles to be written by a single individual.  They also looked for anachronisms and other inconsistencies that might indicate that the traditional writer could not have been the actual writers. In the end however all they have is their analysis.  Archeological and manuscript evidence still favors the traditional writers.

What is the purpose behind attributing the authorship of the Bible to a number of unknown writers? The main purpose is to try to make the Bible look fraudulent.  The second is to try to explain why the Bible contains fulfilled prophecy. If you can demonstrate that the Bible was written by men who were not what they claimed to be, and if you can demonstrate that prophecy after an event happened, you can put the Bible aside as un-authoritative, and of solely human origin.  But in reality, that is not what we find.
How many people wrote the books of Moses?
Some scholars believe that at least four different authors, the Jehovist, the Elohist, the Deuteronomic and the Priestly, (JEDP) wrote the original books of Moses. They tell us that the writings were later compiled by editors centuries after the actual documents were written. This view was first presented in the 18th century, but is not based on any archeological finds. That is, the books of Moses have never been found divided in the way the scholars describe, other than in their own publications.  The interesting thing is that once the books have been re-assigned to different authors there are contradictions. Imagine that. The fact is that the books of the Pentateuch were written as complete works by Moses at the time of the exodus around 1400 B.C. Archeological evidence confirms that the books were in existence in 700 BC, several hundred years before the critics have them coming into existence.
Who wrote Isaiah?
Certain scholars have also made the claim that Isaiah was actually two different people, three different people, or  many different people. The first two are generally accepted among the critics and  have been labeled Isaiah and Deutero-Isaiah. Yet all the copies of Isaiah we have, even ones that predate Christ all present Isaiah as a single book.  There are no copies that split where the critics predicted it would be. In fact they were very disappointed when the book of Isaiah found in the dead sea scrolls showed no division. It demonstrated with physical proof that it had not originally been two or more books as some have suggested.

Why question the authorship of Isaiah? Because it contains fulfilled prophecy. For instance it names the Medo-Persian leader Cyrus over 100 years before he lead the armies that conquered Babylon. It also has prophecies of the coming Messiah, his kingdom and it speaks of moral issues within religion.
Who wrote the Gospels?
Additionally some scholars have made the claim that the Gospels all used a document the call "Q" even though such a document has never been found.  There is however evidence that documents containing information similar to the Gospels were in circulation at the time, but there is no evidence to support whether these documents influenced the Gospels, or the Gospels influence the documents.  The similarities exist because they were all speaking of the same real events.

There is no reason to doubt the traditional authors, and many archeological evidences have been found that support places and people that are mentioned in the Gospels. There is also evidence that the Gospels were written during the lifetimes of the people who witnessed the events they described. The dates that were once given by liberal  scholars of the 2nd century AD can no longer be held. Traditional views of authorship are continually being confirmed, and the views of the liberal scholars overturned.
Who wrote the Book of Daniel?
Some scholars believe that Daniel was written around 165 BC. They pick this date because Daniel has a long list of prophecies that were fulfilled up until that date. What they often don't realize is that Daniel has additional prophecies fulfilled after that date.
Which should make you wonder, how could somebody in the 2nd century BC write real prophecies, while claiming to be someone he was not?

These are some of the reasons they give for dating Daniel in the 2nd century.
Daniel uses Greek and Persian words that would not be known in the sixth century BC, he calls Belshazzar the son of Nebuchadnezzar, and he talks about Darius the Mede, a figure that cannot be directly identified.

The critics look for elements that agree with what they know and believe about history. Therefore they require of Daniel things that either are not relevant, or are simply mistaken.
First, the book of Daniel was translated into Greek around 270 BC, one hundred years before they claim it was written. Secondly, Daniel uses Greek words to name Greek musical instruments, and Persian words to identify Persian political offices. What's unusual about that? Daniel served the royalty of Babylon, who most certainly had access to instruments from other cultures. Daniel was present when the Persians took control of Babylon, and set up their political structure. Daniel is also correct in calling Belshazzar the "son" of  Nebuchadnezzar. Although Belshazzar was his grandson this was and still is in some cultures a correct usage of the term "son". The fact that Darius the Mede is not mentioned in secular history could be that we don't have all the documents, or that Darius the Mede was a title and not a name.  But its not proof that Darius the Mede was not a historical figure.

The reasons given to doubt that Daniel was actually a prophet in the 6th century BC are not valid in most cases and unverifiable in others.
There is no reason to assume the critics are right on any point they raise as to the authorship of the Bible. All the evidences we have point to the traditional views of authorship. If we were to go back 100 years, this would be a different story. At the time, there was far less archeological evidence, and the science of archeology was not as well advanced, and the liberal scholars took advantage of that ignorance by concocting alternate histories which have been proven to be false. As evidence has come to light and been examined the arguments of the critics have lost credibility with those willing to examine it more thoroughly.
All the claims have two things in common, the first is that there is no archeological evidence to support them, and the second is that the main motivation to divide the books up is to question the authority of scripture.  The fact is that archeological evidence and analysis of the text supports the Bible and the traditional views of its authorship.