Is it permissible to listen to Fairuz's (the Christian) songs, including her religious songs such as "I Sang for Mecca"?

It is not permissible for a Muslim to listen to songs accompanied by wind instruments and musical instruments, regardless of the singer or the lyrics of the song. However, if the songs are free of musical instruments and their lyrics are Islamically acceptable, there is no objection to listening to them, as long as it does not lead to something forbidden or the neglect of an obligation. It is forbidden for a non-mahram (definition) woman to sing for men who are not her husbands or mahrams, even if the singing is free of forbidden musical instruments.