Do you know how Islam became widespread?
During the first 10 years as a "prophet", Muhammad preached peace and tolerance because he had no military or political power. In those 10 years of hard work, he converted 100 people. Only ten people a year.
After he started provoking the pagans by telling them that their gods were false and ordering them to convert to Islam, the pagans kicked him out of Mecca (that's the "persecution" muslims always whine about).
Muhammad declared himself a poor refugee and went to Medina, a jewish city. Then, realizing that preaching peace and tolerance wasn't very effective, he became a highway man. A bandit.
He and his followers started to attack meccan caravans, killing the merchants and stealing all their money (the quran legitimized the practice by saying that "persecution is worse than murder", so the muslims could kill and steal to "defend" themselves from the meccan persecution. Muslims still use this logic to this day.)
The more money he got from these attacks, the more people wanted to join his religion, for 3 reasons:
1) so they could get a share;
2) so Muhammad wouldn't attack them;
3) for their war-like mentality, the winner was right. If Muhammad was winning battles, it meant Islam was the true religion.
After 5 years in Medina, Muhammed had killed/enslaved all the jews there and accumulated tens of thousands of followers.
After 10 years, he had accumulated an army and he returned to Mecca, conquered it and forced everyone to choose between converting to islam or dying.
Then he did the same thing to all other towns and tribes in the entire Arabia, unifying all of them under Islam with the sword.
When Muhammad died, his successor continue to pursue the command to "fight the idolaters until the religion will be only for Allah", and attacked Iran, India, North Africa, Spain, Italy, Eastern Europe, etc. Usually winning battles thanks to their superior number and their ferocity and surprise attacks (but getting buttblasted pretty much everytime they attacked westerners, starting from Charles Martel).
Meanwhile, they kept impregnating 2, 3 or 4 wives each, plus lots of female slaves, and shitting out millions and millions of kids that then became soldiers to conquer more infidel lands.
THAT'S how islam spread so much. With wombs and swords. Because of pure, simple, earthly greed.
What about the time Muhammad attacked the Banu Qurayza in 627 d.C.? The men had surrendered, but Muhammad still had them all beheaded, one by one. 700-900 men, all killed for hours on end. Then the women and kids were enslaved. (Source: A. Guillaume, "The Life of Muhammad", Oxford, 1955, p. 461-464. And also the hadith: Abu Dawud 39,4390).
Or what about the time he attacked the Bani Mustaliq without any provocation, so much so that he surprised them without any weapons? His men raped the women and then enslaved them and the kids. (Source: Bukhari 2541 and 4138).
And what about that time he attacked the jews in the Khaybar oasis in 628 d.C.? They were completely unprepared to battle, hadn't done anything to Muhammad, but were still slaughtered because Muhammad wanted their money. To find it, Muhammad even tortured and killed the treasurer. (Source: Ibn Ishaq, Ibn Hisham, “Sirat Rasul Allah”, 757 and 764.)
Yes, Muhammad was such an honorable man.