Complete the following sentence: The Bible was written by...
Most Christians would answer along the lines of "divinely inspired prophets and apostles", but if you're an atheist, the answer is usually "a bunch of bronze age goat herders". However, a worrying trend is emerging in the Church wherein some Christians(?) are more inclined to agree with the latter answer.
The Bible is very clear about its own origins. If you're not a Christian, that isn't very convincing. And indeed, it shouldn't be. That would be circular reasoning, and this article is not intended for you. But if you're a Christian, that should mean everything to you. Take away divine inspiration, what are you left with? At best, you're left with a book with a very ambiguous mixture of facts and fiction. At worst, you're left with a book of the uneducated opinions of primitives. In both scenarios, you're left with no authoritative source of Christian doctrine.
In that scenario, how can you call yourself a CHRIST-ian? A Christian, by definition, follows the teachings of Christ, and Christ repeatedly affirmed the Scriptures. So you're either left with the belief that even He was wrong about some things, allowing you to pick and choose when He was right and when He was wrong, or with the belief that some of the things He is said to have taught (by His Apostles) were not actually what He taught, again, allowing you to pick and choose what you think He did and didn't teach.
Notice how in both scenarios, you are the authority. You're not following Christ, you're trying to make Christ follow you. So how can you claim to be a Christian? I think it is perfectly safe to say that anyone who doubts the divine origin of the Scriptures is, by definition, not Christian. It is essential for such people to repent, because on judgment day, many will call Jesus "Lord", but He will tell them plainly "I never knew you; depart from Me, you who practice lawlessness!" (Matthew 7:21-23). Do not let that happen to you.