I don't remember if it's from a khutbah I heard a while back or an article I read or what have you, but the belief was that all non-Muslims, whether they are Jew, Christian, Hindu etc. at some point in their life they are given an opportunity, some on numerous occasions to discover Islam. The analogy was of a door to Islam.
For some people the door would be locked, those are people that haven't heard of Islam, have no clue what it's about, or they just know it's a religion but just possess no interest in learning it.
For others the door could be unlocked, open a crack or opened fully and the curiosity or quest for knowledge of a person would compel them to approach the door and even walk in. By that I mean a person not too sure about Islam or one that has a distorted image of Islam has a Muslim friend, coworker or someone they interact with that is Muslim and a discussion occurs, or they see something on TV related to Islam that strikes their interest, or they come across a book at a library, a class they are taking where Islam is touched on or compared with other religions, or they see something on the news. They will be given a sort of "key" or invitation to approach that door and it's up to the person's own will whether they want to approach that door and learn more about it, or go on about their business.
Heck, 9/11, though a horrible tragedy, could be seen as a massive open door for the whole world to go discover and learn about Islam. Everyone knows about Islam or Muslims in some way, whether it's the negative "terrorist religion" view or some other view, they know about Islam and it's up to them to go and research it, learn about it and get the facts and try to understand the religion.
Allah gives everyone an opportunity to find the truth in some way shape or form, and if not they are tested in this life and if they do the right thing from the test that Allah gives them, it would count as the equivalent of being a true believer.