Simplify the following text for a Grade 7 native English-speaking person.
Original: The giant wants them to commit suicide , but they endure the ordeal until Christian realizes that a key he has , called Promise , will open all the doors and gates of Doubting Castle .
Simplified: The giant wants them to commit suicide , but they refuse . Suddenly Christian realizes that a key he has , called Promise , will open all the doors and gates of Doubting Castle .