I agree that atheism iitself is no replacement for religion. There is actually a lively debate amongst atheists right now: If not religion, then what? Religion does offer certain things such as a sense of community, comfort from various fears (ie, fear of death etc), answers to the unanswerable, a sense of cosmic justice (that people who do wrong will pay for it even if we can't make them), etc. Most of this can be found outside of religion, but it doesn't come in one ready made package and it isn't always as comfortable, and I think that is a major reason why faith is so attractive to people.
Uncertainty and admitting ignorance can be uncomfortable. It takes a certain sort of humility to accept the limitations of our knowledge and admit that there are some things that we simply do not (and perhaps can never) know. And it can be uncomfortable to realize that we have to build our own justice and that sometimes bad things do happen to good people for no fair reason. The world can be harsh (all the more reason to help each other out). It can be tempting to lean on religion as a crutch against this, which is fine and can be good, so long as that crutch doesn't become a weapon, and doesn't create hostile divisions, and so long as people don't rely on it to such an extent that they fail to create justice and address problems for themselves (instead of relying on the gods).
