Matthew, Mark, Luke, and John, which narrate the life, ministry, death, and resurrection of Jesus Christ.

Yes, the Gospels mention Jesus having brothers (James, Joseph, Simon, and Judas) and sisters (Mark 6:3, Matthew 13:55-56). Interpretations vary on whether these were biological children of Mary and Joseph, step-siblings, or cousins.

The word of God has the power to reveal to us certain things that we could not know in any other way. For example: How and when the world was created. The reason man is the way he is - sin. The true nature of God. What happens to us after we die. Human beings could study and speculate on these things for a thousand years and come up with many theories, but that's all they'd be, just theories...