The Prophet (ﷺ) said, “Whoever builds a mosque, desiring thereby Allah’s pleasure, Allah builds for him the like of it in paradise.” [Bukhari]

 Building a mosque helps us spread our deen in this world and brings not only ourselves closer to Allah (SWT) but everyone who enters the mosque as well.
The Prophet (ﷺ) has told us the reward for building a mosque, we should follow in his footsteps and build masjids for those in need.

Building a mosque provides us with great rewards in this duniya and the hereafter. 

Along with building a mosque there is also a responsibility to maintain the mosque and also spread the deen, and encourage people to come closer to the worship of Allah.