Saint Monica's Church

 is the church in Rivet City run by Father Clifford and his acolyte Diego.

It is possible to break into the church's donation box to steal from it, which results in a loss of karma. The only thing inside is Pre-War Money.

Father Clifford informs the player that Saint Monica is the patron saint of lost children, and this is a major focus of Clifford's theology. Historically, Saint Monica was Saint Augustine of Hippo's mother and the patron saint of difficult children (among other things), but in Fallout Saint Monica was a woman born to ghoul parents.

The Replicated Man
You can find a holotape for the The Replicated Man quest inside the podium

The wedding
You can watch the wedding of anglea Staley and Diego after you give her the Queeen ant pheromon. I am unsure how long you had to wait before you ask anglea but she tells you to be at the chucrh at a certain time.

Appearances
Saint Monica's Church appears only in Fallout 3.