How are you supposed to believe he's an angel when he's far too mysterious and unhinged as hell?

After the death of your parents, you've been harshly bullied until Rajmund, your 'guardian angel' with a red halo comes along to protect you. And by protecting, he killed your bullies and scared all of your friends away.

How the hell are you supposed to believe he's doing this for the 'greater good' when he so proudly does this to anything he deems as a threat, and being everyone??