The anti-Islam protesters were there to protest how Islam is practiced in the Middle East and how that version of it is using the freedom of religion laws of other countries to spread into the rest of the world. But that side was also motivated by a lot of ignorance-based hate.
The pro-Islam protesters were there to defend the freedom of religion, including of religions they don’t personally like. Whether they realize this is happening or not, a lot of Muslims outside the Middle East are reinterpreting Islam to combine its ideas with those of their own countries, including everyone else’s freedom of religion. But their side was motivated by a lot of ignorance-based acceptance, because they assumed that almost all Muslims all over the world practice Islam the way Muslims they like here in the US practice it.
Ayaan Hirsi Ali, an ex-Muslim refugee from Sudan and a political scientist, brings all these topics together in her books and videos. Her most recent book is Heretic–Why Islam Needs a Reformation Now.