Radical Christian hackers have been waging an online war against atheism.
MySpace shut down the group last month despite having promised to keep it up after earlier hack attacks.
The site was put back up in February, but some members are still being barred and some discussions are lost. MySpace has yet to comment on the issue.
"MySpace is running foul of existing laws on religious tolerance," said Terry Sanderson, president of the National Secular Society.
"It is disgraceful that this site was taken down. It is religious discrimination because these actions will protect religious hackers to the detriment of others.
"There is a growing concern from radical Christians about these kinds of atheist websites and they are becoming much more aggressive."
Bryan Pesta, the Atheist and Agnostics Group moderator, started the group in 2004 and claims that it is the largest online gathering of atheists and agnostics.
"We are rebuilding from a recent hacking that banned most regulars and deleted many of the threads that gave us our character," the page states.
"I owe someone at MySpace a thanks for restoring the group, but at the risk of pushing my luck, 'unbanning' the regulars would be really cool too."
MySpace was acquired last year by News International, which is owned by born again Christian Rupert Murdoch.