The Children of Ra is a group of humans who worshiped Supreme System Lord Ra even after his death.
During his time as the Supreme System Lord, Ra often surrounded himself with human children to use as servants. The children in question were indoctrinated with propaganda and remained steadfastly loyal to their God. They also acted as human shields should Ra ever be threatened and could be called upon to do anything their God commanded, with the children themselves serving Ra loyally and without any question. When the original Abydos expedition killed Ra, these children, who were left behind, were eventually integrated into the Abydonian community.
However, unbeknownst to both the Tau'ri or Abydonians, many of them grew up vowing revenge for the death of their beloved god, and began to launch attacks on Earth and Abydos, using their knowledge of Goa'uld technology and a fierce religious fervor to achieve their goals. (RPG: "System Lord Plot Hooks")