What is the ruling on receiving treatment from a Christian priest who treats with herbs to alleviate joint pain and rheumatism, knowing that he does not charge money?

It is not permissible for a Muslim woman to seek medical treatment from a disbeliever unless there is an extreme necessity, such as the unavailability of a Muslim female doctor or a Muslim male doctor. The Shafi'is stipulated that if the patient is a woman, there must be no woman who is skilled in medicine. Furthermore, the doctor must not be untrustworthy when a trustworthy one is available, nor a dhimmi when a Muslim is available, nor a dhimmi woman when a Muslim woman is available. If a genuine necessity arises and it is highly probable that the disbeliever is skilled, truthful, and trustworthy, then it is permissible. However, caution must be exercised to ensure that the individual is not unqualified or among those missionaries who attempt to influence the beliefs of Muslims, as the default assumption for such individuals is suspicion. Ibn al-Hajj mentioned that their religion dictates that whoever among them advises a Muslim has deviated from their own faith.