Explain Why Islam Spread So Quickly

I think that islam spread so quickly because of the taxing of the non-muslims and the trade routes. My first reason why islam spread so quickly is because of taxing the non-muslims. I think that because in the article it says that the merchants and the non-muslims provided the city and the caliphs wealth through their work as a trader and manufacturers . They paid taxes to the caliph, so he could afford money to the armies that protected trade and maintained order in the Umayyad kingdom. My second reason why islam spread so quickly is because of the trade routes. I also think it was the trade routes because Muslims merchants traveled a lot and throughout their areas