Is Hallowe'en Catholic?

Daniel Maclise, Snap-Apple Night (1833) - as Hallowe'en is known in Kerry

As we know it, that is?

In all probability, yes, it is, and the prejudice against it almost certainly has its origins in anti-Catholic bigotry. There is no credible evidence that "pagan" Samhain and Hallowe'en have anything to do with each other. The former involved lighting bonfires to celebrate the Celtic New Year. The latter marks the beginning of the Christian month of the dead. Practices such as porch-watching and souling go back to the Middle Ages, before the rise of Protestantism. In Ireland, souling became guising, and in the Nineteenth Century it crossed over to America where it became modern day trick-or-treating.

In Scotland and Ireland, "guising" — children going from door to door in disguise — is traditional, and a gift in the form of food, coins or "apples or nuts for the Halloween party" (in more recent times chocolate) is given out to the children dressed up in various costumes. The tradition is called "guising" because of the disguises or costumes worn by the children. In the West Mid Scots dialect, guising is known as "galoshans". Among the earliest record of guising at Halloween in Scotland is in 1895, where masqueraders in disguise carrying lanterns made out of scooped out turnips, visit homes to be rewarded with cakes, fruit, and money. Guising also involved going to wealthy homes, and in the 1920s, boys went guising at Halloween up to the affluent Thorntonhall, South Lanarkshire. An account of guising in the 1950s in Ardrossan, North Ayrshire, records a child receiving 12 shillings and sixpence having knocked on doors throughout the neighborhood and performed. There is a significant difference from the way the practice has developed in North America with the associated threat. In Scotland and Ireland, the children are only supposed to receive treats if they perform a party trick for the households they go to. This normally takes the form of singing a song or reciting a joke or a funny poem which the child has memorised before setting out. Occasionally a more talented child may do card tricks, play the mouth organ, or something even more impressive, but most children will earn plenty of treats even with something very simple. Often they won't even need to perform. While going from door to door in disguise has remained popular among Scots and Irish at Halloween, the North American saying "trick-or-treat" has become common.

[Wikipedia] 

And of course the more Catholic a country is the more likely it will be that Hallowe'en is a "thing". "Trick-or-treating" is known today in the Republic of Ireland, Puerto Rico, and northwestern and central Mexico. In the latter, this practice is called calaverita (Spanish for "little skull"), and instead of "trick or treat", the children ask ¿me da mi calaverita? ("can you give me my little skull?") where a calaverita is a small skull made of sugar or chocolate. In St. Louis, Missouri the quid-pro-quo aspect still exists in the local trick-or-treat culture: technically it's trick-and-treat, in as much as that children in the area are expected to perform a joke, usually a simple Halloween-themed pun or riddle, before receiving any candy; this "trick" earns the "treat".

In Portugal, children go from house to house on All Saints day and All Souls Day, carrying pumpkin carved lanterns called coca, asking every one they see for Pão-por-Deus singing rhymes where they remind people why they are begging, saying "...It is for me and for you, and to give to the deceased who are dead and buried[...]" or "[...]It is to share with your deceased [...]" If a door is not open or the children don't get anything, they end their singing saying "[...]In this house smells like lard, here must live someone deceased". In the Azores the bread given to the children takes the shape of the top of a skull. The tradition of pão-por-Deus was already recorded in the 15th century. After this ritual begging, takes place the Magusto and big bonfires are lit with the "firewood of the souls". The young people play around smothering their faces with the ashes. The ritual begging for the deceased used to take place all over the year as in several regions the dead, those who were dear, were expected to arrive and take part in the major celebrations like Christmas and a plate with food or a seat at the table was always left for them. 

[Ibid.]

In Austria, between 30th October and 8th November, Austrians celebrate Seleenwoche (All Souls' Week) by remembering loved ones that have passed away, and leave bread, water and a lamp on a table before going to bed in a bid to 'welcome the dead souls'.

In other non-Catholic countries, Hallowe'en customs go on, but they've been disengaged from Hallowe'en altogether.

In Sweden, children dress up as witches and monsters when they go trick-or-treating on Maundy Thursday (the Thursday before Easter) while Danish children dress up in various attires and go trick-or-treating on Fastelavn (or the next day, Shrove Monday). In Norway, "trick-or-treat" is called "knask eller knep", which means almost the same thing, although with the word order reversed, and the practice is quite common among children, who come dressed up to people's doors asking for, mainly, candy. Many Norwegians prepare for the event by consciously buying a small stock of sweets prior to it, to come in handy should any kids come knocking on the door, which is very probable in most areas. The Easter witch tradition is done on Palm Sunday in Finland. In parts of Flanders and some parts of the Netherlands and most areas of Germany, Switzerland, and Austria, children go to houses with homemade beet lanterns or with paper lanterns (which can hold a candle or electronic light), singing songs about St. Martin on St. Martin's Day (the 11th of November), in return for treats. In Northern Germany and Southern Denmark, children dress up in costumes and go trick-or-treating on New Year's Eve in a tradition called "Rummelpott".

[Ibid.]