Final answer:
Christian loses his certificate after falling asleep on the Hill Difficulty in 'The Pilgrim's Progress', symbolizing the dangers of spiritual complacency.
Step-by-step explanation:
In John Bunyan's allegorical novel The Pilgrim's Progress, Christian falls asleep and loses his certificate on the Hill Difficulty. This occurs after he chooses the steep and challenging path, which contrasts with the easier routes which lead to danger. His falling asleep is a moment of human weakness and symbolizes how believers can become complacent or tired on their spiritual journey.