Unfortunately, I can't answer that question for certain, but considering it was once a Spanish colony, I would think it's safe to assume a good majority of the population is of Catholic origins. I can, however, tell you that almost all of Manila's Spanish colonial architecture was destroyed suring it's battle for liberation during Warld War II during bombardment of the USA Air Force. 
 Quite a bit! Some of Manila's parishes located throughout the city date back to the Spanish Colonial Period! The city used to serve as the base for numerous Catholic missions. The population of the city is 1.78 million people, making it the second-most populous city in the Philippines. 
 I didn't know it was one of the largest cities in Philippines. What can you tell me about its demographics. 
 Thank you, I would like to learn about its sister cities. 
 That is fine, well tell me more about its geography
Quite a bit! Some of Manila's parishes located throughout the city date back to the Spanish Colonial Period! The city used to serve as the base for numerous Catholic missions. The population of the city is 1.78 million people, making it the second-most populous city in the Philippines.