In some countries, non-religious "cultural" circumcision is very common (eg 75% of males in the US [0]). Relatively few cases will be for a medical reason (something like phimosis). Parents in most "secular circumcision" cultures base their circumcision decision primarily on social concerns, rather than medical concerns; the strongest predictor for the decision a couple will make is whether the father is circumcised or not[1]. So your point about religious circumcision being the most common is true worldwide (2/3 of circumcisions are for Muslim men[2]), but there are countries where this is significantly less of a factor.