Full list of all 48 Cult of the Lamb achievements. It takes around 15-20 hours to unlock all of the achievements in the base game on Windows.
The base game contains 37 achievements, and there are 2 DLC packs containing 11 achievements.
Defeat the One Who Waits.
Defeat Shamura.
Cook a Follower meat meal.
Defeat all opponents in Knucklebones.
Gain 20 Followers.
Find all 5 locations.
Take confession.
Unlock all weapons.
Defeat Kallamar.
Unlock all doctrines.
Have 666 gold coins.
Unlock all curses.
Catch 1 of every fish.
Defeat Heket.
Sacrifice a Follower.
Salvation awaits the fallen soul.
Gain 10 Followers.
Unlock a new fleece.
Reignite the lighthouse.
Defeat Leshy.
Win a game of Knucklebones.
A new world awaits.
Gain 5 Followers.
Let the Word be known.
Defeat the first mini-boss.
The first devotee to the Cult of the Lamb.
A deal that cannot be undone.
Beat Leshy without taking damage.
Beat Heket without taking damage.
Beat Kallamar without taking damage.
Beat Shamura without taking damage.
Unlock all Follower Skins.
Unlock all tarot cards.
Sacrifice 10 Followers.
Fully Upgrade Cult.
Unlock all fleeces.
No longer a servant, no less than a God.
Collect all Relics.
Get your Gold back from Midas.
Complete a row in Purgatory.
Unlock all lore.
Unlock all outfits.
Have 12 Disciples.
Completely Upgrade the Temple.
Hatch 5 eggs.