What is the ruling on circumcision in Islam, and how do we respond to those who say it is an innovation, claiming that the Companions were not circumcised, and that Allah did not err in designing humans?

The statement that the Companions were not circumcised and that circumcision is not mentioned in Islam is a blatant lie and profound ignorance. Arabs are a nation of circumcision, and circumcision among them was a remnant of the religion of Abraham. There is no disagreement among scholars regarding the permissibility of circumcision; the only disagreement is concerning its obligation. The argument that circumcision contradicts the creation of man in the best stature is invalid, as circumcision was commanded like the rest of the traditions of innate disposition (fitra), and it has proven health benefits.