That is a question that many ask about Christmas and Easter since, for them, the stories of Jesus' birth and resurrection are so out of this world that they struggle to believe them.
This reminds me of the film Contact.
Contact tells the story of Eleanor ‘Ellie’ Arroway who grew up with an interest in intelligent life in space. Both her parents died while she was young but she later became a scientist, working for the Search for Extraterrestrial Intelligence (SETI) program in Puerto Rico.
Ellie faces oppositions to her work but she eventually finds a strong signal, apparently sent from the star Vega, 26 light years away.
The nations of the world fund the construction of a machine to send someone to Vega.
Ellie is favoured but Christian philosopher Palmer Joss, a panel member with whom she had a brief romantic encounter, brings attention to Ellie's lack of religious faith. As a result, the panel selects a US government scientist. On the day the machine is tested, a religious fanatic destroys it in a suicide bombing, killing the US scientist and others.
Later it is revealed that a second machine is hidden in Japan, and Ellie will be its pilot. Outfitted with recording devices, Ellie is locked into the pod of the machine, dropped into the rapidly spinning, rotating rings, and disappears. When the pod travels through wormholes, she experiences displacement and can observe the outside environment and signs of a highly advanced civilisation on an unknown planet. Ellie finds herself on a beachfront. As she looks, a blurry figure approaches that turns out to be her deceased father.
Ellie tries to ask many questions. As she considers the answers, she falls unconscious. She later awakens to find herself on the floor of the pod. She learns that from outside the machine it appears the pod merely dropped and landed in the safety net.
Ellie insists that she was gone for about 18 hours, which the recording confirms. She tries to convince people that her story is true, but the only person who believes her is Joss, the Christian philosopher.
The truth of Christmas and Easter, and of God, is like Ellie's truth: it is something that one has to experience. I think this is why Joss, a Christian, understands what Ellie is talking about.