I don't like power structures but some are necessary. Take the police for example, a world where the police are not needed would be a better world. Police are a nasty coercive force. And yet they are completely essential.

Religion is interesting because it is obviously not essential in the way that a police force is. However, it isn't yet obvious that it can be done without - a religion's adherents are often people who want some sort of power structure telling them what they should do to be a good person. What it means to be a good person isn't obvious, and in practice is very complex. Sometimes a good person needs to do horrible things - we should be terrified of taking that sort of decision on personally. Sometimes bad people want to do good and would appreciate being told how.

* Political structures aren't strong enough to organise society on their own. They only communicate the beliefs of the current ruling class.

* We can do without a lot of religious dogma, which is clearly wrong (eg, anything talking about purging heretics). We need some sort of shared story for what is going on that looks a lot like a religion.