All Saints Day is a day set aside and marked with tremendous reverence in the Catholic Church, but widely acknowledged by other Christian denominations. For the Catholic Church, it is remembered as a Holy Day of Obligation, expecting Mass attendance. Many different religions and cultures celebrate some sort of All Saints Day.

Growing up in the United Methodist Church, I do not recall celebrating All Saints Day. In fact, it was during my college years that I first learned of All Saints Day when I was director of music for a Lutheran church. When my maternal grandmother passed away in 1992, All Saints Day became particularly meaningful.
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ALL-SAINTS
James Russell Lowell
One feast, of holy days the crest,
I, though no Churchman, love to keep,
All-Saints,–the unknown good that rest
In God’s still memory folded deep;
The bravely dumb that did their deed,
And scorned to blot it with a name,
Men of the plain heroic breed,
That loved Heaven’s silence more than fame.
Such lived not in the past alone,
But thread to-day the unheeding street,
And stairs to Sin and Famine known
Sing with the welcome of their feet;
The den they enter grows a shrine,
The grimy sash an oriel burns,
Their cup of water warms like wine,
Their speech is filled from heavenly urns.
About their brows to me appears
An aureole traced in tenderest light,
The rainbow-gleam of smiles through tears
In dying eyes, by them made bright,
Of souls that shivered on the edge
Of that chill ford repassed no more,
And in their mercy felt the pledge
And sweetness of the farther shore.
Make it a great day!