So in addition to what pretty much everyone else says, you should note the conditions of emergence. Judaism not only doesn't seek converts; the people it considers its followers were a subjugated people. Not in a position to spread anything. And then after the Romans drove them out of their land a couple centuries BCE, they were basically the world's biggest refugee population. Again, not a situation that helps proselytization even if they wanted to do it.
Meanwhile Christianity managed to become the state religion of Rome and basically all of Europe after the collapse of Rome. Added up that's more than 600 years as the state religion of a global superpower (or superpowers) that actually cared to spread their religion. When you also remember how European colonization was a thing, you basically have three continents' worth of Christians and significant populations elsewhere.
Meanwhile Islam came and united the Arabs under one banner. These people, who were only concerned about writing poetry, trade and killing each other for a while, suddenly had both the means and (material and spiritual) incentive to expand. With the two extant superpowers greatly weakened, nobody could do anything about their light cavalry and sheer zeal (remember the Syria crossing?) for a while. You know how the Mongols were united by Genghis Khan and conquered basically everyone? Yeah that's basically how it went. Muslim merchants, with their country now the wealthiest in the world (sans China I don't know much about them in that time period) went everywhere and had a tendency to convert trade partners, which got Islam a foothold in places Muslim rule never reached. BTW here I'd like to correct a common mistake: Islam usually didn't force people to convert. However, Islam was still the state religion and at the top of the socioeconomic ladder, and depending on time and place non-Muslims had significantly harder lives than Muslims. These factors fueled conversions and in a few centuries Islam was the majority religion in these countries.