After divorcing the wife three times, and her apostatizing from Islam, then her desiring to return to it, is it permissible to marry her again, and if that happens, will they have one divorce remaining or three divorces?

If a man divorces his wife with the third divorce, she becomes irrevocably separated from him and is not lawful for him until she marries another husband in a desired marriage, and then he divorces her or dies. Apostasy does not affect this ruling; so, if she was divorced thrice, then apostatized, then returned to Islam, she is not lawful for her first divorcer until she marries another husband.