Nahúm was born on a ranch in Chicontepec (Veracruz). He studied to be a primary school teacher and received a degree in 1959 from the Escuela Nacional de Maestros in Mexico City. He soon discovered his interest in art and enrolled in the Escuela Nacional de Pintura y Escultura (called "La Esmeralda"), taking classes there from 1968 until 1972.
His first one-artist exhibition, at which he showed purely abstract work, took place in Mexico City in 1974. He continued to work as a school teacher in the Mexican capital until 1982, at which time he decided to devote himself full-time to painting and drawing.
Virtually all of his works on paper and (since the early 90s) on canvas, have dealt with his own image. He often includes that of his lover, Gerardo Vilchis, as well. Gerardo invariably plays the role of companion, alter-ego, guardian angel and sexual outlaw in the paintings by Nahúm.
Nahúm has also served as a strong supporter of gay and lesbian social and artistic causes in Mexico. He has projected himself both in his art as well as in his private life as one of the country's most adamant activists in both the cultural and political spheres, and he continues to provide encouragement to many artists whose work deals openly with their sexuality or with issues of sexual identity.
He has maintained a key role in the organization known as the Circulo Cultural Gay which, since the early 1980s, has presented a highly significant event held each June. In 1987, he was one of the founders of the Semana Cultural Gay (Gay Cultural Week)held yearly at the Museo Universitario del Chopo (a beaux-arts structure in Mexico City owned by the National University) in conjunction with the yearly gay rights march in the Mexican capital.