Was the Chrysalids book set in the future?
Yes, it is set in a future post-apocalyptic version of earth. The "old" people they discuss are us, and we have destroyed our world probably with nuclear weapons. The radiation could be what causes all the mutations.
'Actually there are no motifs with in the chrysalids but I will advise you to read the book than to take someone's wrongful judgement.' ..are you kidding? motifs are ideas or themes that are constantly present in a book. EVERY book will have motifs. some of The Chrysalids' motifs include fear, blaspheme, intolerance and telepathy.