How so? I had to read Frankl's book in high school. The more I meditated on it, the more I disagreed with Frankl on an objective level. I thought the reader (like Frankl) would have to be an functional atheist or agnostic to buy into the message.
Did you mean the part about his actual experience, or the logotherapy?
Father Walter Cizek was imprisoned in Siberia for 20 years; he wrote a book called, "He Leadeth Me" where he described his experiences before and after he simply found acceptance and peace in the fact that nothing happens in this universe that is either permitted or ordained by God. I admit, his attitude was more edifying than logotherapy. Yet Frankl used his experience to help others, as well. Similar experiences, different points of view- an interesting contrast...