I'm here not to spread Chaos or serve a dead corpse. I'm here to defend my lands and the free man and women who cannot defend themselves yet the Imperium ignores!
I don't play heretic. I serve no corpse nor daemon. I follow the true purpose of space marines and defend the planets out of the reach of the IoM.
Renegade Marine then? There is only so much a chapter can do without aid from the Imperium or the ruinous powers. Look where the Soul Drinkers ended up.