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 Heket.
Unlock a new fleece.
Reignite the lighthouse.
Defeat Leshy.
Sacrifice a Follower.
Salvation awaits the fallen soul.
Gain 10 Followers.
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.
Gain 20 Followers.
Defeat Kallamar.
Defeat Shamura.
Defeat the One Who Waits.
Beat Leshy without taking damage.
Beat Heket without taking damage.
Beat Kallamar without taking damage.
Beat Shamura without taking damage.
Take confession.
Find all 5 locations.
Unlock all Follower Skins.
Unlock all tarot cards.
Catch 1 of every fish.
Sacrifice 10 Followers.
Have 666 gold coins.
Unlock all weapons.
Unlock all curses.
Fully Upgrade Cult.
Unlock all fleeces.
Cook a Follower meat meal.
Unlock all doctrines.
Defeat all opponents in Knucklebones.
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.