regarding the topic of eliminating religion to create a fair society, the former Soviet Union banned religion, and they were far from an open/just society.
1. Religion was never banned to begin with and it wasn't repressed constantly throughout the whole period - there were times when it was seriously targeted and large period of time, especially towards the end of communism when it was left alone. Yes, churches were destroyed here and there, but the institution of the Orthodox church continued its existence and there never was any real ban on religious beliefs.
2. Atheism was promoted but it was never backed up by the development of critical thinking in children in schools. And without critical thinking, atheism is worthless and it loses its foundations so it becomes very easy for people to be lied by any charlatans once the charlatans are not kept in check by the government any more. Communist countries had the strongest mass educational system mankind has ever seen but those schools developed problem-solving ability in math and a very large foundation of knowledge in the science, but they never really taught the scientific method. To this day, where I come from, exams in the sciences consist of testing your ability to reproduce what was said in lectures and not on testing any real analytical abilities whatsoever. That was still much better than what they do in schools in the US where neither the facts are taught, nor the critical thinking ability is developed, and on top of that, religion is not only not attacked but promoted, but it was still very far from where it should have been. Also note that, on the very high level in the US (the MIT and Ivy League type of institutions) things are in much better shape, while even in the very top universities in the Eastern block, it was still mostly memorize-and-reproduce.
So it is not surprising that the Soviet Union tried to get rid of religion and not only it didn't succeed, but the whole experiment failed - the whole thing simply wasn't done the right way. That's because the system became authoritarian from the very beginning, and in an authoritarian system, developing that kind of mastery of critical thinking skills among the population is not seen as a desirable thing from the people on top (who most likely didn't have much of a grasp of the concept themselves).