Thank you for asking this question.
To put it in simple terms, Christians believe the Bible to be true, but there are differences in exactly what it means to be true.
There are a number of viewpoints about the Bible. Here is a rough overview of what different Christians might believe.
- The Bible is absolutely accurate in everything it says and must always be taken literally . This is called Biblical Literalism. People who believe this believe the universe was literally created in seven days a few thousand years ago.
- The Bible is absolutely true, but it sometimes uses metaphor to get it's point across. A person believing this might take the Creation accounts as conveying important truths but not as an accurate scientific description. This is called Biblical Inerrancy or Biblical Infallibility.
- The Bible is true and accurate when describing God or instructing us, but might inaccurately describe some events such as history of Israel. The stories convey important truths, even if they might not be accurate in every detail. This is called Limited Inerrancy.
- The Bible contains enough information for us to know and follow God, especially the person of Jesus. Again the important truths are there, without the necessity of every detail being correct.
There are virtually no Christians who believe that the entirety of the Bible is fiction. At the very least they believe that the stories in the Gospels (the life story of Jesus) are mostly true.