All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
It is not permissible to enable Christians or any other non-Muslim people to perform their prayers or rituals in a mosque. This is because their prayer includes Shirk and associating others with Allaah The Almighty in worship and this is one of the greatest sins that should neither be approved nor tolerated.
Rather, how can they be performed in the Houses of Allaah The Almighty in which He Enjoined mentioning His Name and that they should be exclusively for Allaah The Almighty Alone?
Allaah The Almighty Says (what means):
Moreover, the Prophet, sallallaahu ‘alayhi wa sallam, commanded the purification of the Ka‘bah, and the area surrounding it from the idols and preventing non-Muslims from circumambulating it. He, sallallaahu ‘alayhi wa sallam, commanded someone to announce that “after this year, no polytheist will perform Hajj and no one will circumambulate the House naked.” [Al-Bukhari and Muslim].
Allaah Knows best.