The “atheism is just another belief” talking point is popular in religious circles because it’s a little mental game they can play to try and make their lack of evidence equal to someone saying they lack evidence. They frame atheism as an assertion that no gods exist, which is therefore equal to a religious person making the assertion that their god does exist. We know that in reality, lack of belief in something (anything) is passive and the default (I’m not gonna believe that lizard people live in the sewers unless you prove it to me), but they try to frame it as an active claim because then it’s just a bunch of people claiming different things.
It’s just another form of deceit they wrap around themselves to hide from the fact that they have no actual evidence of the divine existing.
Agnosticism is not some sort of ‘weak atheism’, it is a completely independent thing, you can have gnostic theists, gnostic atheists, agnostic theists and agnostic atheists. It just means that you believe something can be known about the existence of god vs. you believe nothing can be known about it.