Indeed, Spengler is always thought-provoking. He got me to find Franz Rosenzweig's Star of Redemption and make an attempt to study it. Not easy reading.
I cannot think of any other op-ed pundit who would dare suggest that Muhammed is not the source of the Qur'an, or that the Qur'an might be an 8th or 9th century invention.
Spengler actually posted on jihadwatch. He’s not a bad guy and he is intelligent and well-spoken(written) but he made a mistake in equating Armstrong with Spencer and was overly broad and harsh in his statements about Spencer. Spencer is not who he portrays him to be and I think that’s where this little conflict came about.