Can non muslims enter a mosque?
Yes; non-Muslims may enter mosques, which since the Prophet's time have received and even housed visitors of other faiths.
Non-Muslims can enter a mosque. The mosque is the heart of a Muslim community, a place to pray, learn and meet, and from the beginning it has welcomed outsiders: when the Prophet Muhammad, peace be upon him, built his mosque in Medina, delegations from other communities were received there and were even allowed to stay in the building. Islam describes itself as a mercy to all people, Muslim and non-Muslim, and its treatment of people of other faiths is presented as a mark of that mercy. Visitors are simply asked to respect the space: dress modestly, remove shoes, and avoid walking in front of people who are praying. Many mosques run open days and are glad to explain what happens inside. The articles “The Mosque” and “The Rights of Non-Muslims in Islam” give the background.
Evidence
And We have not sent you, [O Muhammad], except as a mercy to the worlds.
Quran 21:107the Mosque The Mosque The ‘Masjid’ or The ‘Mosque,’ is the base and foundation stone for the Muslim population. It is the place where believers congregate, get to know each other and become a solid community. In each local Mosque, all of the people are known by each other and if one person did notFrom The Mosque — IslamHouse.com. Reproduced with attribution.
Summarised from the cited source · · Scholarly review pending