I am not sure how many Catholic Church are there in Chongqing. I only know of one, Cathedral of St Joseph.
The church can’t be seen from Minsheng Road (民生路). At Minsheng Road, you have to look for a lane, Joseph Lane, which has a descending flight of steps. You will see the gate with “若瑟堂” inscripted on the top of the frame of the gate, like the one shown in the photo
Cathedral of St Joseph
1 Joseph Lane, 272 Minsheng Road, Chongqing 630010
Sunday: 0800 (Chinese)
By Bus: 224, 268, 401, 436, 461 aliight at Chongqing Hotel
By Taxi: The easiest option.