Catholics believe that the Catholic Church has the 'keys to the kingdom' of heaven, and whoever is confirmed to be in heaven is considered a saint. It is a title. And the Church has a process to determine if someone is confirmed to be in heaven. Protestants do not typically hold this view, as they typically do not 'confirm' who is in heaven or not. And as such Protestants have a different understanding when it comes to the term saint, and prefer to refer to the apostles, simply as apostles. Which is why any church which has the word 'Saint' in its name is highly likely Catholic (or Anglican) in this country.