Complex sentence: Rabolú (born 1926 in Tolima, Colombia--died 2000 in Bogotá) claims to have experienced some kind of "spiritual knowledge" in 1952, which supposedly allowed him to foresee the impending collision (or near collision) of earth with this planet.
Split into simpler sentences: Rabolú (born 1926 in Tolima, Colombia--died 2000 in Bogotá) claims to have achieved some kind of "spiritual knowledge" in 1952. This knowledge supposedly allowed him to foresee the impending collision (or near collision) of earth with this planet.