Here is the full list of all 20 Argonus and the Gods of Stone achievements.
Read all journal entries.
Set free the souls of all the Argonauts.
Teleport to and from every temple on the isle.
Light all sconces and braziers.
Talk to every god on the isle.
Unearth a certain ancient skull.
Learn to use a forge.
Steal two things from their owner.
Talk to five gods.
Find and place all the mosaic pieces.
Talk to four gods.
Ride a stallion three times.
Raise the dead.
Talk to three gods.
Talk to two gods.
Talk to one god.
Find all the broken pieces of wrecked ships.
Obtain every takable object on the isle.
Complete all Achievements.
Set free the souls of all the isle's inhabitants.