What is the virtue and status of Zamzam water, and why is it believed that it cures, even though Allah is the Healer?

Allah is the Healer, and He has made Zamzam water a means of healing. This does not contradict reliance upon Allah; rather, it is part of taking the permissible means that Allah has commanded. Taking means does not diminish reliance (tawakkul) nor the essence of monotheism (tawhid); instead, it strengthens them, as scholars have explained.