Is it permissible for non-Muslims to come into our masjid for an open day?
In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
There is a great need for the non-Muslims in the West to understand the message of Islam and see the beauty of Islam. Islam has been misrepresented and tainted by the media. It is the duty of the Muslims residing in the West to propagate the true colours of Islam.
Muslims are encouraged to give da’wah, spread leaflets, wear a smile and be warm-hearted.
Having open days in the Masjid is an excellent method for non-Muslims to feel the serenity and vastness of Islam.
It is permissible for non-Muslims to enter the Masjid even if they are in an impure state. They should be encouraged and not forced to come after taking a bath. This will plant respect in their hearts for the masjid.
And Allah Ta’ālā Knows Best
 فتاوى دار العلوم زكريا ج 1 ص 558 زمزم
(قَوْلُهُ وَجَازَ دُخُولُ الذِّمِّيِّ مَسْجِدًا) وَلَوْ جُنُبًا كَمَا فِي الْأَشْبَاهِ (حاشية ابن عابدين ج 6 ص 367 أيج أيم سعيد)
This answer was collected from DarulFiqh.com, which is operated under the supervision of Mufti Faraz ibn Adam al-Mahmudi, the student of world renowned Mufti Ebrahim Desai (Hafizahullah).