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