MissyB1 - me neither.
In the Catholic tradition, Hallowe'en is All Hallows Eve, and also the feast of All Souls. The next day is the feast of All Saints (Hallows). All Saints Day is a holy day of obligation in most dioceses, meaning attendance at Mass is required.
Neither day has anything to do with evil.
I like iVampire's suggestion of reminding children that God is always with us (and that is the point of All Saints and All Souls too - the promise of resurrection means that even death can never overcome us; God is with us in life and in death, and with us to understand and console us in our loss).
You could add that some other Christian holy days may have been superimposed on already existing feast days because it made sense when replacing existing belief systems with new ones and because the old feasts had grown organically from the turning of seasons, providing handy analogies to aspects of the new Christianity. Obviously Easter corresponds with Passover, but Christmas, All Saints and All Souls are probably superimposed.
The Eastern Churches observe All Saints/All Souls after Pentecost.
I agree with FloralBunting's post, esp wrt the dark arts. Participation in seances, etc was never part of older folk traditions surrounding Hallowe'en. The old feast of Samhain that corresponds with Hallowe'en (All Souls Day and All Saints Day) was the start of the year, a borderline between past and present, old and new, a liminal time when the dead and fairies/spirits could revisit the earth, with people offering foods and attempting to protect themselves by wearing costumes, etc. Under the influence of Christianity, prayers were also offered, and RCs are obliged to attend Mass on All Saints Day.