Here is the full list of all 45 Blasphemous achievements. It takes around 25-30 hours to unlock all of the achievements on Windows.
Witness the last moments of Viridiana.
Unlock the ending A.
Get all rosary beads.
Help the Pilgrim reach his final destination.
Save all Kissers of Wounds.
Beat all bosses without flask consumption.
Cross the Bridge door in less than 3 hours.
Get 100% of the game.
Talk with all the corpses.
Get all sword hearts.
Achieve the maximum level of the Mea Culpa sword.
Achieve the maximum value of flasks.
Bring all the offerings to the Blessed Lord of Salty Shores.
Release all cherubs.
Get all relics.
Get all collectibles.
Bring all the offerings to Lvdovico.
Help Cleofás in his path of redemption.
Beat all the arena challenges.
Get all prayers.
Achieve the maximum value of fervor.
Achieve the maximum value of rosary bead slots.
Buy all skills from the Mea Culpa shrines.
Provoke the meeting between Redento and Cleofás.
Achieve the maximum value of health.
Visit the tomb of The Lady of the Tailed Gown.
Buy all the items of the Candelaria shops.
Hatch the Egg of Altasgracias.
Unlock the ending B.
Beat His Holiness Escribar.
Beat all types of enemies.
Discover all zones.
Beat Crisanta of the Anointed Blade.
Beat Exposito, Scion of Abjuration.
Beat Quirce, Returned by the Flames.
Beat Melquíades, The Exhumed Archbishop.
Beat Esdras, of the Anointed Legion.
Beat the Tres Angustias.
Kill 666 enemies.
Beat Perpetua.
Execute 5 different enemies.
Use the Righteous Riposte 5 times.
Beat the Our Lady of the Charred Visage.
Beat Ten Piedad.
Beat the Warden of the Silent Sorrow.