Mirror's Edge
50 Achievements
1,250
Test of Faith
Complete the game without shooting an enemy
80
How to unlock the Test of Faith achievement in Mirror's Edge - Definitive Guide
The one time when you are forced to use a gun will not count towards this trophy. The trophy unlocks during credits.
As the description says, you must complete the game without shooting any enemies. Playing on Easy difficulty will make surviving without the usage of weapons significantly easier, so this is recommended. When confronting enemies, only use melee with and disarm with . If you disarm an enemy, make sure to throw away his weapon with , as pressing will shoot the weapon. To clarify, you can fire weapons, you just can't hit any enemies, though to be safe it's recommended that you just don't shoot at all.
If you want to check to ensure you haven't shot anyone, then go to the menu with . If it says "So far, you have not fired a shot at anyone" in the top right-hand corner, then you're fine.