That's what a lot of people think, including Alice Roberts by the sound of it.....and she really should know better.
It's easy if you break it down to the root of the words.
Theism is a belief claim.
Gnosticism is a knowledge claim.
There is a difference between belief and knowledge. You can believe something that is false and has no evidence to support it.
Knowledge is something that is demonstrably true ie. comports with reality and has supporting evidence.
Atheism is the non acceptance of the Theist's positive claim. It is not a positive claim that God does not exist.
Agnosticism is the lack of knowledge as to the truth of the claim.
So.....it's possible to be a:
1. A Gnostic Theist (one who makes the positive claim for God and knows for certain that it's true).
2. An Agnostic Theist ( one who makes the positive claim for God but doesn't know for certain that it's true).
3. A Gnostic Atheist (one who makes the positive claim that God does not exist and knows for certain that it's true).
4. An Agnostic Atheist ( one who rejects the positive claim for God but does not know for certain that it's true)
As it's impossible to prove God's existence, one way or the other, then the only honest defendable positions are 2 & 4.
As it's the Theist who is making the positive claim it's up to them to provide the burden of proof to support it.
All most Atheists are saying is that the burden of proof has not yet been reached, so the claim is rejected until such time as sufficient evidence supports it.
It is not saying 'There is no God'.
Phew......I hope that clears things up.
