The god of the Bible is often considered to be an all knowing entity, and virtually all Christians today believe the holy book was inspired by Yahweh in one way or another. Given that humanity has had 2,000 years to expand our scientific, philosophical, ethical, and historical knowledge, it can be said that our collective intelligence is more god-like than our ancestors from Biblical times. Thus, we are in a much better position to determine whether or not the Bible could have been inspired by an omniscient being.
The Bible is full of prophecies regarding the future of Israel, Christianity, and the world in general. Presumably, since only God knows the future, many Christian apologists consider fulfilled prophecies to be proof of divine revelation. However, when reviewing these prophecies and their evidence of fulfillment, their divine origin becomes highly suspect. Here are some examples of commonly cited prophecies and reasons to doubt their validity: 
The Old Testament predicted the existence of Jesus as well as many elements of his life
There is strong evidence the writers of the Gospels added elements from Messianic prophecies to Jesus' life story to make him look good. For example, according to Matthew and Luke, Jesus was born from a virgin. This fulfilled the prophecy described in Isaiah 7:14, "Therefore the Lord himself will give you a sign: The virgin will conceive and give birth to a son, and will call him Immanuel." However, after reviewing the evidence, modern scholars have determined the word "virgin" used in the Old Testament during the time of the Gospel's writing was actually a mistranslation of a word meaning "young woman." This and many other examples of fulfilled prophecies that were never made, strongly suggest that the Gospel writers were merely filling out a Messianic template.
The Old Testament predicted events that took place later in the Old Testament such as the Babylonian Exile
Since much of the Old Testament was compiled and re-edited during and after the exile, it is likely they changed the prophecies to match events that already occurred.
The Old Testament predicted the formation of Israel in 1948
This can easily be explained as a "self-fulfilled prophecy." That is, people had known about the prophecy for thousands of years, so they made it happen once the opportunity presented itself.
The Bible predicted modern events such as 9/11
The 9/11 "prophecy" is a good example of what happens when prophecies are written so ambiguously that they could refer to many different events. Here are two passages that some believe predicted the events of 9/11, which have very little to do with the tragedy:
"The first was like a lion, and it had the wings of an eagle. I watched until its wings were torn off and it was lifted from the ground so that it stood on two feet like a human being, and the mind of a human was given to it." (Daniel 7:4)
"The bricks have fallen down, but we will rebuild with dressed stone; the fig trees have been felled, but we will replace them with cedars." (Isaiah 9:10)
As often happens with prophecy believers, they are quick to find examples of fulfilled predictions, but tend to forget and ignore all of the times prophecies missed the mark. In fact there are many examples of failed Biblical prophecies:
- Isaiah 19:1-8 and Ezekiel 30:12 claimed the Nile was going to be dried up
- Ezekiel 28:26-24 claimed Israel would live in peace with its neighbors (ha!)
- In Exodus 23:31 God promised the Israelites the land "from the desert to Lebanon, and from the great river, the Euphrates—all the Hittite country—to the Great Sea on the west" which never happened.
All in all, there's no reason to believe Biblical prophecies originated from an omniscient deity.
Some Christian apologists also consider the scientific validity of certain Bible passages as evidence of divine inspiration. Here are a few examples quoted from a Christian website:
- At a time when it was believed that the earth sat on a large animal or a giant (1500 B.C.), the Bible spoke of the earth's free float in space: "He...hangs the earth upon nothing" (Job 26:7).
- The prophet Isaiah also tells us that the earth is round: "It is he that sits upon the circle of the earth" (Isaiah 40:22).
- Most cosmologists (scientists who study the structures and evolution of the universe) agree that the Genesis account of creation, in imagining an initial void, may be uncannily close to the truth.
To claim these and other passages in the Bible are evidence of divine inspiration is a bit of a stretch. The Bible was not alone among ancient religious texts in having uncannily "scientific" perspectives on the universe. Consider the Hindu Puranas which describe not only a multiverse, but also proposed a cyclical life of the universe lasting 4 billion years, which uniquely captured the vastness of time.
As many evolution adherents understand, the Bible isn't really a scientific document. It gets so much wrong that it is astounding that anyone would consider it to be one.  Here are some examples:
- Many passages in the Bible seem to indicate the Earth was flat. For example, Deuteronomy 13:7, 28:49, 28:64, 33:17. Job 2:8, 19:4, 22:27, 33:13, 48:10, 59:13, 61:2, 65:5, 72:8.
- In Genesis 1:6-8, the sky was described as a firmament (vault) of water.
- In Leviticus 11:5-6 rabbits are said to "chew the cud" (which they don't) and in Leviticus 11:19 bats are referred to as birds (which they aren't).
The Old Testament contains many laws requiring Jews to cleanse themselves with water before eating, before praying, after defecating, etc. A Christian member of my family has, on several occasions, explained that ancient peoples could never have been so concerned with washing without God's intervention (given their ignorance of germs). However, ancient Egyptians were just as, if not more, fastidious than ancient Jews. In addition, if God was so concerned with our hygiene, Jesus would not have proclaimed "Whoever has bathed is entirely clean. He doesn't need to wash himself further, except for his feet" (John 13:10.) He also wouldn't have said "there is nothing outside a person that by going in can defile, but the things that come out are what defile" after the Pharisees caught him eating food without washing his hands in Mark 7:1-15.
Knowing what we know now about human nature, ethics, science, health, etc. what would you tell ancient humans in order to put them onto a path of righteousness and peace? Wouldn't you teach them that slavery and child abuse are sinful, while homosexuality is not? Well, this is the opposite of what the Bible says. Some may counter that Jesus taught the golden rule, but so did many other sages throughout human history. It was nothing special, and it also wasn't specific enough to hinder Christians from imposing suffering on others. In addition, wouldn't it have lessened human suffering if Jesus taught basic medical information instead of faith healing? Wouldn't it have shown an evolved understanding of human nature if the Apostle Paul taught that women should speak UP in church instead of keeping quiet? The reality is that the Bible says nothing that a person from ancient times wouldn't have been able to write. There is no advanced science, no good evidence for fulfilled prophecies, and no moral codes that reveal it was inspired by an all knowing entity.
Humorous video describing what Jesus should have talked about if he was an advanced being
Refutations of claims regarding the scientific validity of the Bible
Description of failed prophecies
List of scientific and historical inaccuracies in the Bible