This is a typical example of how atheists use the doctrine that they all agree to be true:
If the theists recognized that theism is an ontological doctrine, and that atheism is a political doctrine that opposes theist doctrine for public policy, then their argument would be valid. But they are not keen enough to do that, because it eventually deteriorates their ambition. Christians unwittingly suggest theism is a doctrine when they quote the Bible verse that about believing in Jesus to get to everlasting life in heaven.