Amardeep Singh at his own website:
I don't know if the shooter would have acted any differently if he had really known the difference between the turbans that many Sikh men wear and a much smaller number of Muslim clerics wear — or for that matter, the difference between Shias, Sunnis, and Sufis, or any number of specificities that might have added nuance to his hatred.
As I have experienced it, the turban that Sikh men wear is the embodiment of a kind of difference or otherness that can provoke some Americans to react quite viscerally. Yes, ignorance plays a part and probably amplifies that hostility. But I increasingly feel that visible marks of religious difference are lightning rods for this hostility in ways that don't depend on accurate recognition.
I am not sure why the reaction can be so visceral — perhaps because wearing a turban is at once so intimate and personal and so public? Walking around waving, say, an Iranian flag probably wouldn't provoke quite the same reaction. A flag is abstract — a turban, as something worn on the body, is much more concrete and it therefore poses a more palpable (more personal?) symbol for angry young men looking for someone to target. Whether or not that target was actually the “right one” was besides the point for the Oak Creek shooter.