Maintaining the Masjids is by the Prayer (As-Salah)

Question :

Allâh, the Most High says:
"Verily the Masjids of Allah are only maintained by those who believe in Allah and the Last Day."

What is the meaning of the word 'maintained"? Is it permissible for Kuffar (non-Muslims, disbelievers) to help in building a Masjid? Is it permissible that Christian workers take part in the construction?

Answer:

In reality the maintenance of the Masjids is by prayer (As- Salah), acts of obedience, and I'tikaf (seclusion for devotional worship) in them, as well as other physical and verbal acts of worship. Hence, this Verse is commending those who persistently observe acts of worship in the Masjids by various acts of drawing near to Allâh. This is a testimony to the faith of these people. It has been reported in a Hadith of the Prophet that At-Tirmithi graded Hasan:
"If you see a man who is accustomed (to coming) to the Masjid, then testify to his faith."

This is proven by this Verse (9:18) and for this reason it is not for the Mushrikun (polytheists, idolaters) to maintain the Masjids of Allah.

Included in this meaning is building them from good (lawful) earnings in order to seek the reward. For indeed it has been reported (in Hadiths) that which proves the virtue of building Masjids for the Face of Allâh, the Most High. Concerning those who disbelieve in Allâh, it does not benefit or profit them if they help with wealth in building Masjids. This is due to the nullification of their deeds by Shirk (their associating partners with Allâh). However, if they (the disbelievers) build it with their wealth as charity or they share in its construction, it is permissible to pray in it.

Source:
Ash-Shaykh Ibn Jibreen
Fatawa Islamiyah, Vol. 3 Pages 50- 51