Complex sentence: The next day, Abby shows John that she has coloured in the sun on the Ezekiel's "Chariot vision" engraving and John has a sudden realisation that this could be how the world will end.
Split into simpler sentences: The next day, Abby shows John that she has coloured in the sun on the Ezekiel's "Chariot vision" engraving. After seeing the image, John gets a sudden revelation as he realises that this could be how the world will end.