Flame of fire
is the chosen symbol of the holiness of God (Ex. 3:2; Rev.
2:18), as indicating "the intense, all-consuming operation of
his holiness in relation to sin."
Bibliography Information Easton, Matthew George. M.A., D.D., "Biblical Meaning for 'Flame of fire' Eastons Bible Dictionary". bible-history.com - Eastons; 1897.