Isaac and his mother were happy until the day that Isaac's mother started hearing the voice of God. God told Isaac's mother he was corrupted, so she took away everything from him including his clothing. God told her that wasn't enough to save his soul, so she locked Isaac away in his room. Finally, God called on her to sacrifice Isaac, to show that she loved Him above all else. His mother's reply? "Yes, Lord."
The Binding of Isaac is based on the eponymous biblical story of Abraham and his son Isaac where God asked Abraham to sacrifice his only son, but spared Isaac in the end because Abraham had been willing to make the ultimate sacrifice for Him. Unlike biblical Isaac, the Isaac in this game isn't about to stand for that. He escapes to the basement where he fights his way through various level of horrors. The player takes control of a naked, crying Isaac as he fights through the basement using his tears. Along the way, the player picks up various objects that usually help, though some hinder, Isaac's quest.