Easy Kills Cheat
Hold all four shoulder buttons on the controller (L1, L2, R1, R2) at either the main menu, bonus menu or options menu and a cheat menu will be displayed. Highlight a cheat line then hold X, and press left or right to toggle the letters. Enter the code DEAMONISE. Once you have entered the code, press Square to confirm and Triangle to exit.
God Mode Cheat
Do the same as above, except enter the code MONSTROUS