In the sense that there is no God. What that means is that regarding gods, there are none. Or in other words, the god count is zero, zero being the number of gods, or one fewer god than a monotheist believes exists, and several fewer than a polytheist believes exist. This means that gods are nonexistent, that if there were a foolproof test for gods, the test would yield a negative result. This would be because gods don't exist. That's the sense that they mean it.
No. The knowledge of man is what he has discovered about himself, the world, and the relationship of the two. Gods, if they exist, tell us nothing. People claiming to speak for gods tell us what they believe gods are like. That is not knowledge about gods.
Of course, you might mean something other than what I mean by knowledge. Unjustified beliefs aren't included in my definition.
There is no god of atheists, although I am considering calling reason my god just to communicate with those theists who cannot conceive of what atheism is, and never seem to get it that we have no gods. Why keep telling them otherwise if they can never learn that? It's called validation therapy when dealing with a child, the mentally ill, and the demented. You don't argue with them about their misunderstanding, because they can't hear or understand what they are told. You accept some of their reality in discussion, because you get better results than you would disagreeing with them.
If I do that, I should also probably also call secular humanism my religion.
I think you've been lied to, and by men. The tell you that there is a god, and you believe them uncritically.
Disagree. She knows that she has Y chromosomes and male sexual apparatus. Her mind tells her that she feel like a woman, and wants to look, behave, and be treated like a woman. This shouldn't be an issue for you, but your religion makes it one, and you carry water for it.
Bigotry against atheists and transgendered people can be cold bigotry, in which no malice is experienced. There may even be a feeling of benevolence. It's the bigotry of lowered expectations, of seeing people as inferior and wanting to help them. Think of the father who wants to send his son to university or the military, but thinks his daughter should avoid both, because she doesn't have what it takes or shouldn't be concerning herself with such matters. He probably loves her, but his opinion of her is bigoted. It's misogynistic, yet he probably sees himself as protecting her or guiding her into a life that will make her happier.
That's you. You see both atheists and transgendered people as damaged, spiritually sick people, and you want to help save them from Satan. Is that best called an attack? Maybe not. But it is experienced as condemnation.