A thought that occurs to me is that if one has the belief that all that is real is only explicable in terms of particles and forces, and that nothing exists that is not one of these, then good and bad doesn’t exist either, the same would be true for any concept for that matter. Or perhaps it is only true when reduced to the level of matter and forces, but without the moral force, meaning and purpose that such a materialist only description would entail. After all, if death is forever, which is materialist view, then what does it matter if a seventy or seven year old enters the grave? Their eternal state infinitely outweighs the length of time they were alive and so death at any age, or no life at all, is all the same to an infinite degree! Even the cause of death, or amount of suffering entailed in that death, is of complete inconsequence when compared to infinity of oblivion. In fact any life experience, understanding, thoughts, and so on is infinitely nothing when measured against infinity of oblivion.
Obviously if the only truth is described in terms of forces and particles or some such description; concepts like good and bad don’t apply at such a level. If meaning and purpose don’t really exist, nor does good and bad? What meaning and purpose could there be if the only truth to be had is in descriptions of particles and forces, unless truth also applies to a level of reality beyond a mere description of that which makes up the material universe? They say man is more than the sum of his memories, but could it also be that things are more than the sum of their parts? If so what would explain that? Certainly it couldn’t be on the level of particles and forces! Something more is required. It doesn’t have to be God, although it could be, but at a minimum it would require a third element that is not physical in nature but connects to the physical.
Some metaphysical or other type of realm would seem to be necessary to supply meaning to reality in various ways and it would also be part of reality, or at least connect to it in some way. If not, then meaning and morals do not exist and the inner reality of self is only an illusion. If there is no other world apart from the physical one, and in that reality truth is only a description at atomic levels of particles and forces, it follows that anger at God or religious people for believing in a God is pointless and meaningless. The argument that belief in God harms people or causes wars and so on, should not matter at all because truth doesn’t apply to good and bad but only to the description of material at its smallest level.
So an atheist should probably believe in some form of reality that is not physical in nature as well as the one that is, because if they do not, and they want to say religion is bad or untrue, it would be pointless for them to do so because even their own perception and inner reality is not true but an illusion and as pointless as that they would criticise. A rational atheist would take into account general philosophical concerns, not just scientific ones.