This qualitative study aims to investigate novice undergraduate mathematics students' first encounter with the First Isomorphism Theorem, which is, more often than not, the pinnacle of a typical introductory course in Group Theory. Several studies have reported on the challenges that this mathematical result poses to inexperienced mathematicians, mostly due to the numerous prerequisite abstract concepts. For the analysis of student responses, there has been used the Commognitive Theoretical Framework. This study suggests that the major challenges are due to the comprehension of the notions of kernel, image and isomorphism, and the application of FIT as a routine in the context of proofs.