2 First ye entered into the vestibule of the Baptistery, and there facing towards the West ye listened to the command to stretch forth your hand, and as in the presence of Satan ye renounced him. Now ye must know that this figure is found in ancient history. For when Pharaoh, that most bitter and cruel tyrant, was oppressing the free and high-born people of the Hebrews, God sent Moses to bring them out of the evil bondage of the Egyptians. Then the door posts were anointed with the blood of a lamb, that the destroyer might flee from the houses which had the sign of the blood; and the Hebrew people was marvellously delivered. The enemy, however, after their rescue, pursued after them, and saw the sea wondrously parted for them; nevertheless he went on, following close in their footsteps, and was all at once overwhelmed and engulphed in the Red Sea.
Source: Catechetical Lectures (New Advent)