The Christian Church appropriated ,any pagan thing and rituals such as the Winter Solstice (Christmas), the Spring Equinox (Easter), and the sites of henges and sacred groves to build their churches. Many of raw principle figures and legends (Jesus and his miracles) were reworking of older (Egyptian and Babylonian) stories.
Holy festival
Santa, Presents, Decmeber, snow, and trees. Christmas is a celebration of the birth of Christ. He was actually born in May/June, put the some pope changed it to December to stop pagans from celebrating a festival.
In the society depicted in "The Giver" by Lois Lowry, people stop celebrating birthdays at the age of Twelve. This is when they are assigned their adult roles in the community and begin their training for their designated professions.
Who? As far as I know, Christmas is still celebrated everywhere there are Christians.
St. Patrick is not known for stopping violence in Ireland. He's known for converting pagans to Christianity.
Never stop celebrating holidays that you love! However, trick-or-treating should probably end in the mid- to late-teens, as some candy-givers may feel threatened or uncomfortable by adults that dress up to get candy.
Perhaps Saudi Arabia (which doesn't allow Jews, period).
The Catholic Church.
your question is not clear , are you asking at what age do youth stop attending the catholic church?:S
Halloween is actually a corruption of All Saints Eve (from the Old English - All Hallow's Eve), as such it is a Catholic Feast and the Church has never tried to get people to stop celebrating it, they have just tried to get people to celebrate it correctly and not concentrate on demons and mythological spirits.
The Roman Catholic as an organization did not like the developments that led to the Reformation. It did attempt to stop it in many instances.
That really depends on what government you are talking about.