For many Christians, especially those whose traditions do not observe the church calendar, the mere mention of "All Saints' Day" sounds eerily Roman Catholic or taboo.  But what exactly is this feast day (i.e., church celebration) all about?  I have found no better short explanation than that in the Treasury of Daily Prayer:

This feast is the most comprehensive of the days of commemoration, encompassing the entire scope of that great cloud of witnesss with which we are surrounded (Heb 12.1).  It holds before the eyes of faith that great multitude which no man can number: all the saints of God in Christ--from every nation, race, culture, and language--who have come 'out of the great tribulation...who have washed their robes and made them white in the blood of the Lamb' (Rev 7.9, 14).  As such, it sets before us the full height and depth and breadth and length of our dear Lord's gracious salvation (Eph 3.17-19).  It shares with Easter a celebration of the resurrection, since all those who have died with Christ Jesus have also been raised with Him (Rom 6.3-8).  It shares with Pentecost a celebration of the ingathering of the entire Church catholic [i.e., 'universal church' not 'Roman Catholic church']--in heaven and on earth, in all times and places--in the one Body of Christ, in the unity of the Spirit in the bond of peace.  Just as we have all been called to the one hope that belongs to our call, 'one Lord, one faith, one baptism, one God and Father of all, who is over all and through all and in all' (Eph 4.4-6).  And the Feast of All Saints shares with the final Sundays of the Church Year an eschatalogical focus on the life everlasting and a confession that 'the sufferings of this present time are not worth comparing with the glory that is to be revealed to us' (Rom 8.18).  In all of these emphases, the purpose of this feast is to fix our eyes upon Jesus, the author and perfector of our faith, that we might not grow weary or fainthearted (Heb 12.2-3).

: : : : : : : : : : :