The fourth existential question that a good theology must answer is why is there suffering?
The Christian answer is because there is sin in the world beginning with the Original Sin of Eve and Adam and so human beings must redeem themselves, and like Jesus, suffer at the hands of a punitive God who punishes human beings when they do things that displease Him.
The Buddhist answer is that suffering is caused by attachment.
The Humanist answer is that life is harsh, brutish, and short because that's just the way it is.
I don't know that Unitarian Universalism has an answer for the question of why there is suffering so they tend to deny it and pretend it doesn't exist and think that if they are just nice enough to everyone, suffering will go away.
I distinguish suffering from pain. Pain is an indication that something is wrong, needs attention, and to be healed. Suffering is the interpretation and meaning that people make about pain and usually makes pain worse.
Suffering is not a natural thing and is brought about mostly by humans themselves who have a dysfunctional theology which teaches that suffering is warranted as in "You should be ashamed of yourself" and "you made your bed now lie in it" and "what did you do to deserve this?" and God had suffering inflicted on His own son to save the world so what makes you so special?
The Universalists did not buy into the notion that suffering is deserved and is good for people's souls. At the time, it was a radical idea which disrupted widely held Calvanistic beliefs that people get what they deserve.
A theology based on the original blessing like the Creation Spirituality of Mathew Fox directly refutes the idea of original sin and it got Rev. Fox excommunicated from the Roman Catholic Church, but he continues on as an Episcopal Priest. Would Unitarian Universalism espouse a theology of the original blessing? It does already with its first value of the inherent worth and dignity of every person. However, Unitarian Universalism has a long way to go to explain the ubiquitous experience of human suffering in theological terms.
The spiritual practice to end suffering is probably something akin to the 12 step program wherein people are encouraged to surrender to their Higher Power whatever they conceive their higher power to be, and to take life one day at a time. The Buddhist practice of mindfulness also is very helpful for suffering. Prayer that recognizes that we are a part of an interdependent web of existence and therefore can "rise above it" because "this too shall pass" is a frame of mind that brings peace as it is cultivated.
I am reminded of the frequent distress of people who feel like a victim and say, "Why did this happen to me?" The answer, of course, not in a callous or dismissive way, but in a pensive and reflective way, is "why not?"
As the bumper sticker says, "Shit happens". It happens to all of us, and miraculously when we recognize that fact, it becomes OK and our suffering decreases if not is eliminated.
This is article #4 in a series on David G. Markham's theology.