Q: Can a non Muslim enter a masjid?
A: It is permissible for a non-Muslim to enter the musjid provided he is adequately dressed and in a sober state. This applies to kuffar men only. Kuffar women are not allowed into the musjid for purdah reasons, just as Muslim women are not allowed to attend the musjid.This ruling applies to all musjids besides the Haramayn Shareefayn. Kuffar will not be allowed to enter Musjidul Haraam in Makka or Musjidun Nabawi in Madinah.
And Allah Ta’ala knows best
Mufti Siraj Desai
Darul-Uloom Abubakr
Port Elizabeth
South Africa