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