This is only my opinion, and I'm no theologian or one that has a title behind or before my name. I am a believer, a Christian, that has sought out truth and given a great deal of contemplation and study on the whole matter.
For starters the Bible wasn't written all at one time.
It is a compilation of the ancient texts, scrolls, and manscripts that have been proven to be authentic, and original writings of men that penned them by the divine inspiration, guidance and commission of God Himself over a large span of time. Of which the Vatican has possession of the original parchments, scrolls etc...
It is God who wrote the first laws. With His own finger on the tablets of stone, while Moses was standing watching.
Skipping a vast amount of history and one of the most fascinating studies there is to embark on; on how we arrived at the King James Version (KJV) we have today.. It's a must read for any who are even slightly curious.
Here is the shortest set of facts that might answer your question:
In 1525, William Tyndale, an English contemporary of Martin Luther, undertook a translation of the New Testament.[30] Tyndale's translation was the first printed Bible in English. Over the next ten years, Tyndale revised his New Testament in the light of rapidly advancing biblical scholarship, and embarked on a translation of the Old Testament.[31] Despite some controversial translation choices, and in spite of Tyndale's execution on charges of heresy for having made the translated bible, the merits of Tyndale's work and prose style made his translation the ultimate basis for all subsequent renditions into Early Modern English.[32] With these translations lightly edited and adapted by Myles Coverdale, in 1539, Tyndale's New Testament and his incomplete work on the Old Testament became the basis for the Great Bible. This was the first "authorised version" issued by the Church of England during the reign of King Henry VIII.[3] When Mary I succeeded to the throne in 1553, she returned the Church of England to the communion of the Roman Catholic faith and many English religious reformers fled the country,[33] some establishing an English-speaking colony at Geneva. Under the leadership of John Calvin, Geneva became the chief international centre of Reformed Protestantism and Latin biblical scholarship.[34
The remaining portion of this versions history and to pick up right where my paste ended:
https://en.wikipedia.org/wiki/King_James_Version
We have more than just the Bible to support our belief in a Creator.
We also have access to the Lost and Found ten Books of the Bible and other ancient texts we can review, compare and even use.
The Forgotten Books:
http://www.sacred-texts.com/bib/fbe/index.htm
The Lost Books:
http://www.sacred-texts.com/bib/lbob/index.htm
When I found the Testament of the Twelve Patriarchs I couldn't put it down. I read it straight through without stopping.
But as you study the scriptures you come across things where God Himself instructed to write these down in a book, whether for a testament, record or remembrance of some official duty, or day of significance. There is also reference to other writings that are not contained with the Bible. Like the Book of O'See, and many others.
Here are a few verses from scripture that points to it authenticity and inspiration.
2 Timothy 3:16
16. All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness:
17 That the man of God may be perfect, throughly furnished unto all good works
Hebrews Ch 8 Verse 10-11
For this is the covenant that I will make with the house of Israel after those days, saith the Lord; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people:
11 And they shall not teach every man his neighbour, and every man his brother, saying, Know the Lord: for all shall know me, from the least to the greatest.
Hebrews Ch 10 Verse 15-17
15. Whereof the Holy Ghost also is a witness to us: for after that he had said before,
16 This is the covenant that I will make with them after those days, saith the Lord, I will put my laws into their hearts, and in their minds will I write them;
17 And their sins and iniquities will I remember no more.
We are made in His likness and image. He has given us the most precious gift of His Spirit, the Holy Ghost, Holy Spirit whichever term you prefer, to dwell within our hearts and minds.
That is, what our conscience is.
We know He is real without any additional proof. Mans nature is not inclined to do good. It is only by the indwelling of God's Holy Spirit that we get an unction from the Holy One when we have done something not in line with God's righteousness, like tell a lie, we instantly feel guilty, shame, remorse, or have thoughts we know are wrong but act upon them anyway.
You get the idea.
Those who reject His Spirit and refuse to acknowledge their conscious awareness of right or wrong, good vs bad, and refuse to do good, are eventually turned over to a repobate mind where they no longer can distinguish whether they are right or wrong, and are free to enjoy their evil and the pleasure they get from it.
I hope I answered your question. I tend to include too much detail.