I disagree here. Saying you believe something is different that saying you know something.

If you someone says they "don't believe there are giraffes in space", they are almost certainly really saying that they "don't expect there to be giraffes in space", or perhaps that they "don't think there are giraffes in space".

And that's what atheists mean when they say they don't believe in God. They don't know with 100% certainty that the God of Abraham exists, but they see little to no reason to expect that the God of Abraham exists.

Now, if you told me at the beginning of a conversation that, "For the duration of this conversation, the word 'believe' must only be used if you are 100% certain of something", then sure, I would avoid using the word 'believe' if I wasn't 100% sure of something. But that's really not the way people typically use the word.

And if you think about it, nobody can ever really be 100% sure about anything, so if we truly demanded 100% certainty every time the word 'believe' was used, it would end up being a pretty useless word.

To that end, if you think someone who says they 'believe' something is being dishonest, I'd say that's more your fault as the listener than the fault of the speaker.

The likelihood that the God of Abraham exists, I think, is less than 1 out of 100. Less than 1 out of a million even. And that's why I think it's totally fair for me to say that I don't believe in God without being labelled as dishonest.

Conversely, does an average Christian truly believe with 100% certainty that God exists? I find that hard to imagine. If put to the question, I wonder what most Christians would actually say the odds are of their God existing. My guess is that, out loud, they'd say "100%", but in their hearts, most would find the question uncomfortable, and would try to push the thought out of their mind.