Answer
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
There is nothing wrong with accepting donations from Christian neighbors to complete the construction of your community mosque.
Answering your question, Dr. Ali Suleiman Ali, Imam and Director of the Muslim Community of Western Suburbs, Canton, Michigan, and a co-founder, Core Scholar, and member of the Board of Trustees of the American Learning Institute for Muslims (ALIM), states:
Yes, you can accept donations from Christian neighbors for building a mosque. This is based on the following:
1- Our Prophet Muhammad (peace be upon him) had accepted a gift from Muqawqis, the King of Egypt, as well as the King of Rome at the time when they are non-Muslims. Donation is a gift. Muslims jurists unanimously agree that you can accept a gift from non-Muslims just as you can give a gift to non-Muslims
2- The prominent four jurists did not differ in accepting wasiyyah (bequest) and waqf (endowment) from a dhimmi (a non-Muslim living in a Muslim society).
3- The Qur’an has established mutual kindness between Muslims and non-Muslims who are not hostile to Muslims. We read in the Qur’an:
{Allah does not prohibit you respecting those who have not fought for the religion and who have turned you out from your homes, that you show them kindness and act equitably towards them—} (Al-Mumtahanah 60:8)
Some few scholars hold that you cannot take donations from non-Muslims for building mosques. I am not going to present their arguments here because this is not a research paper it is just answering the question.
Almighty Allah knows best.