If most American Christians hope in the same things American non-Christians do (and I think he is right in saying this) then it is no wonder people rarely ask the reason for the hope that we have. If I value the same things as my unbelieving neighbors it is not because the Bible is unclear about what it means to follow Jesus.
I am particularly burdened by this chapter because I have too often fallen into what Piper calls an "avoidance ethic." I ask "What's wrong with it?" instead of "How will this help me treasure Christ more?"
Rather than answering my discussion questions, I prefer to play off of the things you underline or highlight in this chapter. Please mark up your books, especially noting the things that make you uncomfortable.