Why do Atheists care what others believe or do not believe? How does it affect them in the least? The main reason is because they are attempting to try and convince themselves of the nonsense they spew yet intrinsically know to be false due to their own conscience. Nevertheless, according to Atheism, Atheists are their own law givers. Therefore, they cannot impose their "moral standards" on others, since they have none. If God does not exist, then everything is fair game and nothing is wrong or immoral. Atheists who attempt to impose certain moral standards are being inconsistent with what they claim to believe (or not believe) and hypocritical because they are borrowing heavily from Christianity.
Morality is not determined by society. If moral standards were left to men to decide, everyone would do what was right in his/her own eyes. Nobody would agree. Look at modern society where many of its people are complete idiots who think all opinions are equally valid and all "truth claims" are equally valid. What if two opinions are diametrically opposed? Are they still equally valid? What if two "truth claims" are diametrically opposed? Are they still equally valid? Even these ludicrously asinine arguments are inconsistent and hypocritical. So their argument results in, "all opinions are equally valid until they are not" and "all 'truth claims' are equally valid until they are not." Sheer idiocy! But then I would expect nothing less from Atheism.
Morality and moral absolutes come from God. We know these things to be wrong because God has said they are wrong and He has written this fact down in our hearts and on our consciences. How many people have tried to argue for the legitimacy of their murdering people? eating people? molesting children? stealing? lying? committing adultery? It does not matter the sin (or crime), there are people who have tried to argue that there was nothing wrong with it. People today are doing it with homosexuality, transgenderism, Islam, etc.
If Atheists were consistent with their beliefs (or lack of), then no morals would be imposed upon them and they would act accordingly. If we are nothing more than protoplasm and animals, then what does it matter what we do to each other. Especially since when we die we become dust and no longer exist. Why be nice to other people and try to help them if we are nothing, our life means nothing, and we turn into nothing? Why try to better humanity or progress anything (technology, science, health, etc.) since our existence is meaningless and will not amount to anything. Why leave things to future generations when their existence is as meaningless as our own? All you do is create false hope where there is none. You are born, you live, you die. So be consistent Atheists and stop stealing from Christianity and trying to impose Christian morals at will whenever it pleases you and you agree with them. Stop being a Jellyfish Atheists and develop a spine and live your life consistent with Atheism.
Atheists are not trying to convince others that God does not exist; they are attempting to convince themselves. Yet their conscience informs them that He clearly does and that everything they do holds them accountable to Him and that they will answer for everything they have done. People choose Atheism because they do not like to think and having to weigh the evidence and discern what is and is not true is hard work. Why put in the effort to determine who is and is not telling the truth about life and history when it is much easier (and spineless) to dismiss it all and pretend it does not exist despite all the evidence screaming at them?