From the logical scientific stand point, unless you can see the soul, how would you know it was the same soul being thrown back?
Many of the mystery schools were trying to figure out the truth of reality. Many took this too far, at least by any human decency standards.
On the flip side, the main reason most mystery school followers get pulled in is because they see the brutality and seeming chaos of nature and are seeking desperately to find an intellectually satisfying and spiritual explanation for our existence. Once you have seen the devastation of our existence wrought on innocence, probing the workings of existence is not so hard to understand. The Rosicrucianist also believed in the idea of Karma, so causing the death of a child would be problematic unless you determined you wanted to experience that yourself in another life.