How can God forgive sins? How can God change the past? How can God make the defiled undefiled?
By His Grace, the purity that existed previously is made to survive impurity, thus destroying impurity just as Life survived death and thus destroyed death. Absolution in the Mystery of Forgiveness is a participation in the Resurrection where the sinner rises to new life just as Christ rose to new life. The sin never existed. The previous purity is made to survive and sin ceases to exist. It is no longer in the person's past. The person is no longer a sinner. They are pure again by this participation in the Resurrection where Life tramples death by death.
Hristos voskrese iz mertvih, smertiyu smert poprav, i sushchim vo grobeh zhivot daruvav.
Christ is risen from the dead, trampling down death by death, and on those in the tombs, bestowing life.