Lieutenant Rahms, the German officer who conducts Corrie's hearing, is a decent man who "cannot bear the work (he does at the camp)". When he meets Corrie, he is amazed that, after months of terrible suffering, she tells him about a "God (that) values us not for our strength or our brains but simply because He has made us". She appears to draw a sense of strength and peace from her faith which he, as one who has power over her, has never known. The Lieutenant wants Corrie to tell him more about God and the Bible because he hopes that he too can find the comfort she so obviously possesses.
The Lieutenant is a tormented man. He lives in "great darkness", worrying constantly about his wife and children in war-torn Bremen, asking himself each day if they are still alive. He tells Corrie that although he might "appear to...(be) a powerful person...(with) a certain authority over those under (him)...(he is) in prison...a prison stronger than (the one she is in)". Lieutenant Rahms is speaking both physically and metaphorically; the prison in which he is held captive is the visible one at Ravensbruck, where he is forced to enact horrific injustices against innocent human beings; it is also an interior one of the soul. He does not understand how Corrie can believe in a loving God who can allow people to suffer so, but she unquestionably does, and draws great solace from her faith. Lieutenant Rahms wants to experience the incomprehensible and unconquerable peace that sustains Corrie, and hopes that he might somehow find it by hearing more about the God she loves, through the Bible that tells His story (Chapter 11).
The answer that dymatsuoka gave was good except that the prison Corrie met Lieutenant Rahms in was not Ravensbruck. It was Scheveningen. Chapters 10 and 11 of The Hiding Place are written about Corrie and Betsie's prison stay in Scheveningen.