The number cited is 270 million
I found the relevant passage in book you cited, which reads: "“We will be studying the deaths of 270 million Kafirs over 1400 years in jihad. That’s 60 million Christians, 80 million Hindus, 10 million Buddhists and 120 million Africans of varying religions.” I don't know how 270 million became 170 million.
This itself cites Mohammed and the Unbelievers, Bill Warner, CSPI Publishing, 2010, pg. 160. I also have found the relevant passage in this book.
References are provided, but are a mixture of fabrication and misuse of sources
Mohammed and the Unbelievers provides the following references:
- "Thomas Sowell estimates that 11 million slaves were shipped across the Atlantic and 14 million were sent to the Islamic nations of North Africa and the Middle East."
- It's probably true that North Africans captured well over a million slaves over 1300 years, but Thomas Sowell is a right-wing cultural commentator, not a scholar of slavery. Sowell cites the actual source: Ralph A. Austen, "The trans-Saharan slave trade: a tentative census." The Uncommon Market: Essays in the Economic History of the Atlantic Slave Trade (1979). Another historian has objected to these figures: Joseph Inikori, "Africa in World History: The Export Slave Trade from Africa and the Emergence of the Atlantic Economic Order," in B. A. Ogot, ed., Africa from the Sixteenth to the Eighteenth Century (Berkeley, Calif., 1992). Inikori says that 15.4 million slaves were brought to the Americas in the Atlantic slave trade, and only 4 million to North Africa. In any case, these figures do not include deaths, and I only linger here because this is the closest we are going to get to reality.
- "The renowned missionary David Livingstone estimated that for every slave who reached the plantation five others died by being killed in the raid or died on the forced march from illness and privation. So, for 25 million slaves delivered to the market, we have the death of about 120 million people. Islam ran the wholesale slave trade in Africa."
- Here you can see the first clear factual errors. Warner has added Sowell's two figures together, but the "11 million slaves shipped across the Atlantic" were brought by Christians, not Muslims. This already reduces his estimate by half.
- I think to back up his thesis that the Atlantic slave trade -- which often involved selling Muslims to Christians -- was an act of jihad, a citation is provided for the claim that "Islam ran the wholesale slave trade in Africa": a book about slavery in the Middle East by Bernard Lewis, the Orientalist. No page number is given. This is a misuse of the source, because Lewis' book says nothing about the Atlantic slave trade.
- Needless to say, David Livingstone ("Dr. Livingstone, I presume?") was a 19th century colonialist and not a scholar of slavery either. I don't even think he was speaking above his station here, he was just making a general observation that Warner has interpreted as a technical figure. Considering the mention of the "plantation," I also wonder what type of slave raid Livingstone was specifically discussing.
- "The number of Christians martyred by Islam is 9 million [citation to "World Christian Trends AD 30-AD 2200"]. A rough estimate by Raphael Moore in History of Asia Minor is that another 50 million died in wars by jihad."
- Two citations which are both less and more creative than the previous claims. The first is a citation to a table in a book of Christian demographics, which also shows oddly precise stats like "31,689,000" Christians being killed by atheists, but does not provide any breakdowns for any of its figures. The second is a citation which @AlabamaScholiast pointed out is not a book and is not entitled History of Asia Minor, but is actually a religious essay entitled "In Memory Of The 50 Million Victims Of The Orthodox Christian Holocaust" by Father Raphael Moore. This article makes only minimal mention of Islam; the "50 million" estimate is a guess at the number of all Orthodox Christians killed in the 20th century, including 3.65 million people killed by Turkish ethnonationalists (hence the "Asia Minor" subhead), but mostly behind the Iron Curtain, including the Holodomor as a mass extermination. This article does provide a specific number of Orthodox Christians killed by Islamists in Egypt: "dozens." The effects of Islamic extremism on Egypt's Orthodox population should not be understated, but this is not the same as a general holy war by all Muslims on all Christians, and "dozens" is quite different from 50 million.
- "Koenard [sic] Elst in Negationism in India gives an estimate of 80 million Hindus killed in the total jihad against India."
- I have already dealt with this claim in another Skeptics answer. There is no evidence given whatsoever for the figure of 80 million -- it's largely based on another nonexistent quotation.
- "Buddhists do not keep up with the history of war. ... Jihad killed the Buddhists in Turkey, Afghanistan, along the Silk Route, and in India. The total is roughly 10 million."
- The first sentence is not only false but idiotic; historically, Buddhists engaged in wars of aggression in Myanmar, Sri Lanka, Tibet, etc. and recorded it in their chronicles. The sole citation again goes to "World Christian Trends AD 30-AD 2200". Again, this book doesn't say where exactly it gets its figures.
We can see an interesting kind of legitimization occurring in the path this "170/270 million" figure took from the fabrications of a self-published lunatic fringe book, to Crisis magazine, to Stack Exchange itself.