It is sometimes argued against by observations from neuroscience: that people with brain injuries or diseases suffer can suffer quite severe personality changes. Therefore our personality is dependent on our physical state and therefore (it is argued) our consciousness is nothing more than a by-product of the interaction of our brain cells.
I counter that this is reading more into the evidence than is warranted. Just because our consciousness is affected by our physical state, and does not follow that our sense of identity is any less god-given or miraculous - just as our life is no less god-given although it eventually ends.
Besides, such personality changes do not completely affect our identity. I am still "me", despite such personality changes which may happen.