Okay kiddo, let me explain what great apostates are.
An apostate is a person who used to believe in something or belonged to a particular group, but then decided to leave or stop believing it altogether. So, a "great apostate" is someone who was once an important or influential person within a group or community but then left or spoke out against their beliefs.
For example, some people consider Martin Luther to be a great apostate because he was a monk who went against the Catholic Church and started a new form of Christianity, Protestantism. Another example could be Galileo, who was a scientist who went against the beliefs of the Church and said that the Earth revolves around the sun instead of the other way around, which was a big deal at the time.
Sometimes great apostates are seen as heroes or rebels because they stood up for what they believed in, even if it meant going against the norm or facing consequences. Other times, they are vilified or shunned by the communities they left behind.
So, that's what great apostates are - people who were once part of a group or community, but then left and made a big impact by doing so. Does that make sense?