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