Adam's sin can be celebrated insofar as it plays a part in a greater narrative that makes the true story of God and Man more profound than it ever could have been without sin. In other words, sin occasions an enrichment of the end of Man.
Meditating on the Passion with St. Alphonsus Liguori
"Jesus on the cross! Behold the proof the love of God; behold the final manifestation of himself, which the Word Incarnate makes upon this earth,--a manifestation of suffering indeed, but, still more, a manifestation of love."
Lenten Meditation: In the Footsteps of Saints
This Holy Season of Lent is a time to walk after the saints in penance and fasting in order that, becoming increasingly detached from worldly goods and delighting more and more in heavenly goods, we might grow in holiness and love for God.
Faith and Reason 