The Bible answers you clearly. It appears you refuse to believe it.
Here is an example:
Luke 1 Since many have undertaken to set down an orderly account of the events that have been fulfilled among us, 2 just as they were handed on to us by those who from the beginning were eyewitnesses and servants of the word, 3 I too decided, after investigating everything carefully from the very first, to write an orderly account for you, most excellent Theophilus, 4 so that you may know the truth concerning the things about which you have been instructed.
Luke says he decided to write his gospel. He investigated. He talked to eyewitnesses. God didn’t write the gospel of Luke. The Bible says he didn’t.
Why do you disbelieve the Bible?
A Bible believer is someone who believes the Bible. If you believe God wrote the book of Luke, then you are not a Bible believer.
And look at Ephesians 1.
Paul, an apostle of Christ Jesus by the will of God, To God’s holy people in Ephesus, the faithful in Christ Jesus: 2 Grace and peace to you from God our Father and the Lord Jesus Christ.
A “Bible believer” believes Paul wrote the book of Ephesians. A person who doesn’t believe the Bible claims God wrote the book of Ephesians.
Which are you? Do you believe the Bible? If so, then you know God did not write the Bible.