This old one...
This word exists due to historical reasons
Well... it all started with the word "atheism" or "atheist".
During roman times, an "atheist" was a person who didn't believe in the roman gods.... christians were labelled "atheists". You can already see that the concept of a god is... not well defined, but let's try to keep it within the realm of contemporary popular definition - the entity or entities responsible for creating and controlling the world around us, lowly humans.
At some point in history, along the second half of the second millennium, "atheist" became attached to people to claim the non-existence of any god - the believer in the non-existence of gods.
But philosophers just need to keep poking holes and this position became one of faith... one of belief... the very thing those atheists didn't want to be associated with.
Enter the more intellectually honest position, "I don't know and it doesn't look like it's knowable".... the agnostic.
Most agnostics then follow through with "hence, I also withdraw belief in the existence of any divine entity", thus becoming what we like to call "agnostic atheists", or as some would have it "weak atheists".
Some people realize the impossibility of knowing anything about the god of their society, but still can't escape their indoctrination into belief... enter the "agnostic theist".
Some people, mostly in the Americas, find that "atheist" retains that "believe that god does not exist" connotation and choose not to use that label on themselves. But they retain the "agnostic" label, as an equivalent of what I described as "agnostic atheist". It's a strategy to avoid a public shutdown at the mention of the word "atheist".
This word exists due to historical reasons

Well... it all started with the word "atheism" or "atheist".
During roman times, an "atheist" was a person who didn't believe in the roman gods.... christians were labelled "atheists". You can already see that the concept of a god is... not well defined, but let's try to keep it within the realm of contemporary popular definition - the entity or entities responsible for creating and controlling the world around us, lowly humans.
At some point in history, along the second half of the second millennium, "atheist" became attached to people to claim the non-existence of any god - the believer in the non-existence of gods.
But philosophers just need to keep poking holes and this position became one of faith... one of belief... the very thing those atheists didn't want to be associated with.
Enter the more intellectually honest position, "I don't know and it doesn't look like it's knowable".... the agnostic.
Most agnostics then follow through with "hence, I also withdraw belief in the existence of any divine entity", thus becoming what we like to call "agnostic atheists", or as some would have it "weak atheists".
Some people realize the impossibility of knowing anything about the god of their society, but still can't escape their indoctrination into belief... enter the "agnostic theist".
Some people, mostly in the Americas, find that "atheist" retains that "believe that god does not exist" connotation and choose not to use that label on themselves. But they retain the "agnostic" label, as an equivalent of what I described as "agnostic atheist". It's a strategy to avoid a public shutdown at the mention of the word "atheist".