If you want to take an intellectually safe position—to never run the risk of losing an argument over the existence of God*—then agnosticism is the place to pitch your tent. But that’s all it is—an intellectually safe place to hunker down. No one knows for sure whether God exists, even those who claim to talk to Him regularly. “Knowing” isn’t what makes a person’s answer to the God question meaningful. If God’s existence were subject to scientific proof beyond a reasonable doubt, there would be no agnostics. Anyone who claims to know beyond a doubt—one way or the other—is obviously delusional. What matters isn’t knowing whether there’s a God or not, it’s how you choose to live your life.
We have two “as if” choices: (1) We can live as if there is a Deity, or (2) We can live as if there is not. Of course, this is overly simplified. There are many other possibilities. There might be gods who exist but don’t give a damn about us. These Wraiths may “exist” in some passive way and every 15 billion years or so, arise from their slumber and make a new universe. They don’t reward us, or punish us, or care what we do, or worry about what happens to us. They don’t give a hoot whether we believe in them or not, and they don’t legislate morality, give advice, prevent floods, or answer prayers. If gods like these exist, their existence can be safely ignored. As with leprechauns, for example.
An Activist Deity is the type we need to be concerned about. If there’s a God who intervenes in human affairs, and judges all of us at the end of our lives, and then sends our bodies or souls somewhere for eternity, then we’d be stupid to ignore such an Entity. That sort of God might take being ignored as a personal slight—She might want to be worshipped and prayed to five times each day. You’d be smart to live your life paying Her the appropriate homage and respect and doing whatever She wants you to do. To do the otherwise could be Eternally Dangerous.
Atheism then is the dangerous alternative. After all, it could get you sent to a Very Bad Place for a Very Long Time. Is it really any safer to be an agnostic? Perhaps not. For all we know, an Activist God might find agnostics more objectionable than atheists. She might not like weasels.
Atheists don’t claim to know that God or gods exist. Atheists believe, as a working hypothesis, that God does not exist. They run whatever risks that might be entailed in holding firmly to such a mistaken belief. Does it take courage to be an Atheist? I don’t think so, but there are those who find it scary.
* Singular or plural; male, female or both; include any/all the permutations you’d like.