What is the explanation of suffering?

HINDUISM

Karma and Maya: we always reap what we sow, and the suffering we receive is always what we deserve for or misdeeds in this or in previous incarnations; may (illusions) cause us to feel confused, unhappy; Maya leads us to do things which bring us our bad karma.

BUDDHISM: HINAYANA 

Karma, desire, and the illusion of Self; we reap what we sow; the illusion of self causes us to desire things; when we are disappointed we suffer; when we try to meet our desires, we create bad karma which brings suffering.

BUDDHISM: MAHAYANA

The same as Hinayana Buddhism.

TAOISM

Our going against the Tao, forcing our will upon nature so that nature must "strike back" to restore its equilibrium.

CONFUCIANISM

Our lack of wisdom; our failure to follow the ways of the ancients so that our relationships become painful and frustrating.

JUDAISM

When human beings rebel against the will of YHWH, they bring disaster upon themselves. Originally, the emphasis if Judaism was that suffering was a sign  that God was punishing and individual for his sinfulness. As the faith developed, it came to be more and more emphasized that human beings are tied into larger units of family, clan,  nation and humanity; and that one person's sin may lead not to  his suffering, but to others' sorrow.

ISLAM

Much the same as Judaism, with, perhaps, more emphasis on the inscrutable will of Allah. Whatever happens in this world has been decreed by Allah; one doesn't so much seek an explanation for suffering as simply accept it and submit to the will of Allah.

CHRISTIANITY: ORTHODOX

Much like Judaism, but with a difference: the New Testament hints at the idea that God is still in the act of creation and that the natural universe is itself still "incomplete": the natural world of floods, earthquakes, et, can be a dangerous place. Like the Jews, too, Christians stress the inter-relatedness of life: one man's genius may enrich many lifes; one man's selfishness may mar many lifes. But Christianity, more than Judaism -- although this idea is found also in Judaism -- believes that suffering can be transformed by God's love into a blessing: out of evil, God can create good if his people will trust Him with their pain. Without danger, we could never be brave; without suffering, we could never be compassionate; and so forth. The supreme example is the crucifixion of Jesus: by any measure, it was a tragedy, a miscarriage of justice an agonizing death, the failure of a good man; but out of the cross came "resurrection" and the cross, itself, has become a symbol of love and mercy and unending forgiveness.

CHRISTIANITY: ROMAN CATHOLIC

Same

CHRISTIANITY: PROTESTANTISM

Same