The initial article was a comment on the "miraculous" victory of the Christians at Lepanto.
Harpseal used this to make two observations about Islam;
the Islamic war machine conquered most of what is now Islam militarily
One either converted to Islam or faced death
I commented that the same two observations applied equally to Christendom. Nothing either of you has said contradicts the first point...and the exceptions to the second point apply equally to Islam.
That said, I'm not really interested in the fine points of the treatment of the Indians - Catholics vs. Protestants, English vs. Spanish. To what extent la leyenda negra is true will be disputed long after we're gone. It is enough to observe that, human nature being what it is, there are plenty of non-Spanish mestizos in the North. I meet them all the time (or maybe they're lying about their Indian ancestry because it's chic to do so).
Everyone tends to forget that the advance into Syria, Mesopotamia and North Africa (including Egypt) took place within the Dark Ages where even in the most civilized parts of the world record keeping had more or less fallen apart.
We do know that Islam spread to Indonesia rather peacefully - via the ministrations of trader/missionaries. It's being spread rather non-violently in the Americas these days.
Moslem conquest in the Indus was, according to Hindu sources, violent. According to Moslem sources, less violent. Moslems also have some interesting things to say about the Hindus in that regard, and when you notice that low ranking jots and castes were the first to join Islam, there's every indication that most of the reports were exceedingly biased in light of pre-existing social problems in the Sub-Continent.
Getting back to the Eastern Mediterranean experience, Christianity was not as firmly fixed as we might presume. The Persians had never been Christian, and their most popular religion, Mithrism, was widespread throughout the Roman Empire although it was on it's deathbed as was the third competitor we now call Druidism (ever since the 4th Century). The Arien Heresy was popular, and in some areas the only Christians around were actually hermits in the wilderness - they wrote letters which is why we know about them, but that doesn't mean there were a lot of them. Judaism was a popular belief system as well. Even today tribes in Yemen and down the East coast of Africa recall that their religion before Islam was, in fact, Judaism. Various Saudi Arabian groups have a similar tradition as do many, many groups in Afghanistan and Iraq. Their transformation from Jews to Moslems is not, from the Christian theological point of view, a serious item.
Islam has had it's period of greatest growth in recent decades, and for the most part the expansion has been peaceful. Christianity has also been spread peacefully for the last 200 years. The last really violent Christian outburst was fomented by the King of France who used the powers of state to spread Catholicism among Protestants within his Domain. Most of our Bill of Rights consists of items directed against his theory and practice of tyranny (the activities of French kings being much on the minds of our Founding Fathers).
The "spread by the sword" story was certainly excellent propaganda. A good bit of that sort of thing was done by the Mongols, but they would have done it if they'd been Buddhist. In fact, Islam may well have tempered the Mongol approach to conquest - earlier in history they'd been really bad!
One of the major Mongol invaders was, in fact, a Christian - his mother had been a Christian, and those old boys seemed to leave it to their women-folk to inculcate belief. Folks in the areas under his rule became Christian whether they wanted to be or not.
The Spanish situation is exceptional. The Reconquista was very organized and folks took whatever religion the local ruler thought they should have. This went on for centuries and ended only in 1492. Everyone who did not like the final outcome was free to leave, which they did. Loose ends, if we can call them that, were disposed of by the Inquisition (which has a remarkably small death-toll for the times). In the end Spanish social problems were resolved by emigration to the new empire in the West. Troublemakers saw fit to discover America on their own.