Kristof, as a writer, should know that words aren't as powerful as the real thing, i.e., the concept they represent.  For example, saying "You are free" to a slave isn't the same as setting that slave free. Similarly, giving the world a word isn't the same as giving the world a mathematical development.

The word "algebra" might have indeed come from the Arabic language at the time of Islam's ascendancy, but "algebra" is just a word and Kristof tells the reader that he is writing about this word — a very fine gift to the world, he implies (as though other languages were short of words).

However, the branch of mathematics known as algebra (which is surely what Kristof meant to say) had been evolving for centuries before the coming of Muhammad, the founder of Islam. It developed from the earlier works of other civilizations, notably that of India.

Perhaps if Kristof understood that the "outstanding culture and science" he writes of was largely appropriated from other, older cultures (now mostly eradicated by the dominant Muslim culture) in that area, he woudn't be so surprised to find underachievement there now.

It's a disgrace that so many supposedly intelligent people perpetuate the myth that the "golden age of Islam" produced a flowering of art and science.  Robert Spencer refutes this here.

Algebra was actually invented in India, it was merely translated by a Muslim.

Aristotle's works were actually translated, and thereby preserved by Syrian *Christians*. The Christians were critical in keeping the tradition alive.

"Islamic" architecture is by and large taken from the Byzantines.

"Islamic" poetry is taken from the pre-Islamic Arab tribalists.

The Sufi tradition is strikingly similar to that of the Gnostics.

Islam sweeps in and then takes credit for past cultures. Those other cultures deserve credit for their own inventions.

I'm the recent anonymous, and I forgot to mention the obvious, which is the Persian influence on Islamic literature and poetry, among other things.