Longest Night Worship Services gather people and hold sacred space for grief and lament. We mourn with those who mourn, we sorrow over our own griefs, and lament the griefs of our communities and world.
It is not coincidence that just a few days after the longest night, Christians celebrate the Light that broke (and breaks) into our darkness. Already on the day we pay tribute to the birth of Jesus nights are beginning to shorten.
Often I rushed into the joy of Christmas morning without having held vigil during that longest night. In fact, only recently did I learn of services of lament and grief. Still, for a long while I have been keenly aware of the darkness that Christ came (and comes) into, and the last few years have made that poignant for us all. I long to wrestle myself into a sitting posture and accept the invitation to name my griefs and sit in the darkness, even while acknowledging Christ's coming didn't promise to take away troubles or to keep more grief from coming.
And that's the crux of it. We wait in the darkness, and while the darkness cannot overshadow the Light, our joy on Christmas sometimes seems feigned. Sometimes the Light seems to merely flicker against the dark.
The Advent cry, “Come, Lord Jesus,” that echos throughout Christian history acknowledges that while what we long for will come, it is not promised to come now or even soon. We live knowing our lives will be incomplete, knowing we will not find the fulfillment for which we long, that we will always yearn, we will always be carrying our own, another's, and our world's pain on our shoulders, in our guts, and in our hearts.
Is it foolish to hold steadfast to a God who does not give now (or anytime soon) what is promised? Might it be even dangerous in its fatalism? Christianity has been critiqued heartily for that very thing by Karl Marx, Sigmund Freud, and Friedrich Nietzsche (to name a few). But stay a moment, if you can.
Walter Brueggemann, an Old Testament scholar, is one who asserts such steadfastness is neither foolish nor misguided. Christian hope trusts in what God has done and will do, even in the face of wondering if God is disinterested or powerless.
Hope in gospel faith is not just a vague feeling that things will work out, for it is evident that things will not just work out. Rather, hope is the conviction, against a great deal of data, that God is tenacious and persistent in overcoming the deathliness of the world, that God intends joy and peace. Christians find compelling evidence, in the story of Jesus, that Jesus, with great persistence and great vulnerability, everywhere he went, turned the enmity of society toward a new possibility, turned the sadness of the world toward joy, introduced a new regime where the dead are raised, the lost are found, and the displaced are brought home again. 
Richard Rohr continues this thread when he says, “Come, Lord Jesus” is a leap into freedom and surrender that is rightly called hope.
Hope is the patient and trustful willingness to live without full closure, without resolution, and still be content and even happy because our satisfaction is now at another level, and our Source is beyond ourselves. We are able to trust that Christ will come again, just as Christ has come into our past, into our private dilemmas, and into our suffering world. Our Christian past then becomes our Christian prologue, and “Come, Lord Jesus” is not a cry of desperation but an assured shout of cosmic hope.
After you reflect on that, consider this.
Maybe it's helpful to know what's happening on the longest night. Winter Solstice is the day the northern hemisphere reaches its farthest point away from the sun (this happens June 21st for the southern hemisphere). In an instant, on December 21st (7:59ish a.m. in the Pacific Northwest this year), Earth begins to journey toward the sun. The Winter Solstice has been, and is, celebrated around the world as the birth of the new solar year. We are reminded every year not only that light comes after the darkness (even though darkness will return), but also that we are held in a gravitational orbit by the sun. Even when we are farthest away, we are held, warmed, and given enough light to make it through the dark, even if seemingly only just.
Some years we gather friends to celebrate the Winter Solstice, as we will this year. We share good food, and then wander down to the gazebo, the way lit by lights that chase enough of the dark away to keep us from stumbling. We will sit by a fire, drink mulled wine or hot apple cider and share stories, poetry, music and art inspired by this very long night and by our knowing that every day will hold a little more luminescence, even though we are just entering winter.
I wonder what it would be like to blend these two traditions and honor the darkness by mourning our personal and collective losses, and then celebrate that morning indeed follows the night, that birth follows death, and that our hope is not, in the end, in vain.
As grace and mystery would have it, that choice to mourn and also to accept inevitable pain and unfulfilled longings paradoxically puts us on a journey marked by joy unspeakable and hope immeasurable.
 Walter Brueggemann, A Gospel of Hope, compiled by Richard Floyd (Westminster John Knox Press: 2018), 104–105.
 Richard Rohr, Preparing for Christmas: Daily Meditations for Advent (Franciscan Media: 2008), 2–3.