Full Idea
I would say that that my consciousness doesn't seem either physical or non-physical, ..but the belief that the mind is non-physical partly took hold because that fits well with thinking of human agents as free.
Gist of Idea
People largely came to believe in dualism because it made human agents free
Source
Owen Flanagan (The Problem of the Soul [2002], p.102)
Book Reference
Flanagan,Owen: 'The Problem of the Soul' [Basic Books 2003], p.102
A Reaction
I think this is right. I personally think there is no such thing as free will, and that belief in it has been the single greatest delusion amongst philosophers (and others) for the last two thousand years. Dualism has now gone, and free will is next.