While this practice is primarily cultural, some religions do include FGM as part of their practices.
According to Egyptian Al-Azhar University scholar Sheikh Muhammad Al-Mussayar "First of all, there are reliable hadiths in Al-Bukhari and Al-Muslim which support female circumcision. The Prophet Muhammad said: 'If a circumcised woman and man have intercourse, they must undergo ablution.' Unreliable hadiths do not cancel out the reliable ones. We have unreliable hadiths regarding prayer, fasting, charity, and pilgrimage. Should we abolish prayer and charity just because some hadiths are unreliable? According to some hadiths in Al-Bukhari and Al-Muslim, 'If a circumcised woman and man have intercourse, they must undergo ablution.' People would curse one another by saying: 'You son of a clit woman' - the son of a non-circumcised woman. The objections to circumcision are illogical and unnatural."