This cheat involves editing a game file. Always make a backup before making changes to original game files. Also note that this file may be "READ ONLY". You will need to go to the properties of the file and uncheck "read only" before making your changes. Locate the "default.ini" file in your game folder. Open it with Notepad and make the following changes:

God Mode
For god mode, find the following lines and change the values to 0.0:

[Difficulty]; Player Damage multiplier - damage player takes from AIs
Difficulty_Player_Damage_Easy__d=1.0
Difficulty_Player_Damage_Normal__d=1.0
Difficulty_Player_Damage_Hard__d=1.25
Difficulty_Player_Damage_Real__d=1.75

Easy Kills
For easier kills, find the following lines:

AI Damage multiplier - damage AIs take from player
Difficulty_AI_Damage_Easy__d=1.25
Difficulty_AI_Damage_Normal__d=1.0
Difficulty_AI_Damage_Hard__d=0.75
Difficulty_AI_Damage_Real__d=1.5

And change the values to:

Difficulty_AI_Damage_Easy__d=4.25
Difficulty_AI_Damage_Normal__d=4.0
Difficulty_AI_Damage_Hard__d=4.75
Difficulty_AI_Damage_Real__d=4.5