Whose life was in danger in Exodus 4:24 and why?

Answer From The Annual Reading Schedule - Week 14 Notes For Exodus: It appears that Mosheh (Moses) had not circumcised at least one of his sons and that he was in danger because of this. It is possible, as I have heard some speculate, that Tsipporah (Zipporah) his wife, and the people of Midyan (Midian), may have possibly viewed circumcision as barbaric and therefore did not understand the need to circumcise the sons at 8 days old. However, we don't really know for certain why this situation occurred because we don't have all the details. I don't know if those views about the Midyanites (Midianites) are even accurate or not since the Midyanites descended from Avraham's (Abraham's) wife Qeturah (Keturah) who probably were taught about circumcision. However, the danger of Mosheh's life does seem to be related to the circumcision as we see from Exodus 4:26 that he was let go after the child was circumcised.