Why do we celebrate All Saints Day?

Catholic answerEveryone who is in heaven is a saint - be definition, there is no way you can see God without being perfect. We know that there are far more people in heaven than are on the calendar (the people who we celebrate as Saints), therefore to celebrate all those who have gone to heaven but do not have their own day on the calendar we celebrate All Saints Day.

All of those who have died in the grace of Jesus Christ, loving God, and with no mortal sins on their souls are going to heaven but many did not die perfect - as saints. God, in His infinite mercy purifies this people so that they can enter heaven. They are certainly not consigned to hell just for not being perfect. They died in a state of grace, attempting to attain perfection. The process by which God purifies these souls is know as purgatory. We don't know a whole lot about it, just that there is a stage between death and heaven in which God purifies them. The Bible clearly teaches that they are helped by our prayers, thus we remember them on All Souls day and pray for them.

All Saints' day was instituted to honour all saints, including those who have not been canonized. All Souls' Day was instituted for the souls in purgatory. The Mass on that day is offered for them.