As with science and metaphysics, history is a method of inquiry that arises because human beings ask questions. Christians, Jews, and Muslims are summoning everyone to believe in life after death, and this book sheds light on that question. Aslan says the Resurrection of Jesus occurred three days after his crucifixion by Roman soldiers in 30 CE. My understanding is that historians can trace this historical event only to within a few years of his death. The Resurrection of Jesus is also called the Easter experience, and refers to the renewed fellowship of Jesus' disciples after they scattered in fear and shock. It is both an historical event and an object of faith.
Aslan confirms that Jesus was an exorcist and healer. He makes the historicity of this clear by pointing out that Jesus did not charge for his services, unlike other exorcists and healers of his day. He also confirms that Jesus was a popular preacher, and that his disciples founded the Catholic Church with Peter, James, and Paul being the initial leaders of the organization.
Aslan also confirms that Jesus preached the coming of the kingdom of God, but he has his own ideas about what this meant. The meaning of this is relevant to a decision about what religion to follow. I don't think the meaning of this has any relevance to the more general and more important question. What is relevant to this question is that the Bible says in Exodus 3.14 that God's name is "Yahweh" in Hebrew.
"Yahweh" is translated into Greek and English as "I am who am." Thomas Aquinas in the 13th century explained that God is a pure act of existence. A finite being has an existence limited by its essence. This is evidence that God inspired the human authors of the Bible because Jewish people at that time did not comprehend the meaning of the Exodus passage. Another sign that God inspired the Jewish people is that by the time of Jesus, Jewish people believed in life after death.
Another reason to believe our freedom is before God is an historical artifact: the Shroud of Turin. Within decades after Jesus' death, documents said that Jesus was beaten, tortured with a thorn-cap, and stabbed in the side. In addition, these documents say he was put in a separate tomb with a linen burial cloth. The Shroud of Turin tells this same story of the death and burial of Jesus with the blood marks and body image on a linen cloth, front and back. According to In Search of the Shroud of Turin: New Light on Its History and Origins by Robert Drews, a group of unorthodox Christians created the relic in the 1st or 2nd century using a crucified victim to create the blood marks. The method used to create the body image has been lost to time. Many Christians believe the mysterious image was created miraculously 3 days after Jesus died.
The Catholic Church achieved political power in the 4th century, and gave mankind Western civilization. When the Catholic Church lost some of its political influence in the 18th century, the wars and genocide of the 19th and 20th century followed.