Here is the full list of all 24 God Mode achievements.
Complete your first Oath
Finish any map with 3 or more active Oaths
Finish any map on any difficulty
Decapitate 100 Skeletons
Kill 50 enemies using melee
Purchase your first weapon upgrade
Kill 100 creatures
Kill 2500 creatures
Destroy 50 scarab eggs before they hatch
Enrage 10 Cyclops
Trigger 20 Mage seals
Grind 50 creatures using the Buzzsaw melee attack
Reach the final level and attain God Mode
Survive the "Death" Test of Faith
Purchase all upgrades
Fully upgrade one weapon
Finish any map with 6 active Oaths on hardest difficulty
Kill 20 creatures using the Hammer ability
Complete all maps on hardest difficulty
Complete any map without dying
Kill 25 000 creatures
Buy Super Pants
Collect 5 000 000 unspent gold
Complete any map on Platinum difficulty