Episode 31: Sin (2003 series)

Synopsis
Envy reveals the truth to the homunculus child, and with Izumi's secrets exposed as well, the Elric brothers try to stop their teacher's plan of atonement.

Trivia

 * This episode has the first appearance of The Eye of God, with it looking the same as it's manga counterpart but being purple in color while in the manga is a reddish shade of pink (or a pinkish shade of red).