On the first day of November, the Catholic Church honours all the saints, known and unknown. In Polish tradition it is a rather solemn holiday. We also celebrate the following day, All Souls' Day.
At this time of the year it is common to visit graves of relatives, pray for their souls and decorate their graves with special grave lights and flowers (chrysanthemum is popular). This is my tradition because I'm Polish and Catholic.
I'm aware that people around the world have different cultural and religious traditions. It is very easy to judge other people and their beliefs, especially when they are different from ours. So instead of judging or copying traditions, learn more about them.
On October 31st many people celebrate Halloween. For the average Pole it's a ghost festival. It's the common misconception.
The names Halloween and All Hallows' Eve (the Eve of All Saint's Day) come from the Old English halga, which means "saint", but the origins of the festival trace back to the ancient Celts who celebrated the end of summer on that day. In the mid-8th Century it was christianised, as Pope Gregory III moved the date of All Saints' Day to November 1st.
Between 1500-1800 Halloween traditions included bonfires (to guide Christian souls in purgatory), fortune telling (even of romantic nature) and souling (children went from house to house praying for the souls of the dead). By the end of the 17th Century the festival lessened in importance.
Halloween came to the United States probably with the Irish emigrants during the Great Potato Famine in 1845. Of course, it was adapted to local conditions, e.g. turnips were replaced with pumpkins. Also the modern form of "trick or treating" was born in the US. It's worth remembering that Halloween celebrates the harvest season. It represents the beginning of autumn, the season that marks the transition from summer into winter (from life to death).
I think we don't have to worry that Halloween will replace our Polish traditions some day. I have no right to decide whether children in Poland should celebrate it or not, but they definitely should learn about it.