One undeniable argument for the Bible that is absolutely puzzling to skeptics are the martyrs for Christ. These people were threatened with death, and actually died for what they believed in and yet, they believed it anyway. What other reason would there be if what they believed were not the truth.
"Imagine if I had an instrument of torture in my hand and approached a witness. I would easily get the truth out of them! Nobody is going to lie in the face of something like that. But the disciples all went to their deaths and suffered great persecution while proclaiming, 'We have seen the risen Christ.' 'We are not followers of cleverly invented fables,' wrote the Apostle Peter. The Bible tells us he and the Apostles “were eyewitnesses of His majesty." John writes:
"That which we have heard, which we have seen with our eyes, which we have looked at and our hands have touched—this we proclaim..." It was the blood of the witnesses that sealed the truthfulness of their testimony."
"Tertullian, an early Church “father” (and likely a lawyer) wrote, "The blood of the Martyrs is the seed of the Church." He was right. Even in trial law, in the laws of evidence we have the principle of a "dying declaration." A dying declaration is a particular form of evidentiary testimony that is afforded a high level of veracity if heard by a bystander. Thus, even though it is technically "hearsay" (the dead person cannot appear in court to tell us), it's considered reliable evidence if reported by a third party. A third party can stand up in court and testify, "I heard this. Smith said, while he was dying from the car accident, 'But I had a green light.' This is allowable evidence and considered reliable in a modern court. Why? The answer is that when someone is dying or under extreme pressure, it's unlikely they will lie about the last thing they say. That principle validates much of the testimony of the Apostles. What is the point, in the face of death and torture, to give false testimony about Jesus? There is none. Almost all of the early witnesses suffered this fate and not one of them recanted their testimony about Jesus, His life, His miracles, or His resurrection. Doesn't that tell you something?" (Excerpt from Consider the Evidence pg 63-64)