PREAMBLE
We will look at how much religion says that if there is no God of love, mercy and justice that means that no matter who you are or what harm you do you are exonerated. If there is no justice, no wrongness then simply, "It is what it is." Such says that if atheism is correct, we cannot put justice and love into the universe for they are not there.
Against that some say that we do not need to assume a God to consider justice and love and punishment to be valid. These would say that you may not be exonerated in the sense that your good or cruel action does not matter at all. But you are exonerated in the sense that you will not answer for it before a God who will administer justice.
For mainstream religion, God is not like a person in any meaningful sense. He is an it. God is a mind without any kind of material existence, no body. It is confusing how religion still promotes him as if he were a person or someone we can relate to. One way it attempts this is by trying to ground justice and mercy and love in him. It fails for he has no body and no emotions. The fact is that we respond to "he" and "God loves you" and feel something and feel he is in a relationship with us but that does not make God personal. Do not be emotionally seduced by this. See past the incoherence.
It is safe to say that atheists deny there is a big person out there who made all and religion does too in its own way. The point is that you do not need a personal God to affirm moral categories such as just and love.
JUSTICE IS NOT CLEAR SO NEITHER IS EXONERATION
Is everybody no matter how harmful they are exonerated totally or largely if there is no God to administer justice? Only a being can exonerate. Justice and wrongness and rightness have to exist in the first place before you can be exonerated by this being.
And even if they do exist, God can give you the benefits of exoneration without exonerating.
How?
He already does if Jesus' "revelations" to St Paul are to be believed. There you can manage a pass mark of repentance and you get forgiveness for abusing somebody perhaps horrifically and Jesus atones making you as if you never ever sinned. Commonsense says not to trust an enemy who repents 51%. So here we have God trusting them as well as if the victim does not matter.
Also, mercy means letting the person go free if they lose their memory of an evil thing they have done or don't have time to repent. That happens us all at the moment of death. We have to get the benefit of the doubt. "Perhaps Jake would have repented given another second. That he had plenty of time before now is not the point."
Does God exonerate those who think he does not exist? Does he reward them that way for at least being sincere albeit wrong? If the biggest thing about wrongdoing is that it insults God and rejects his authority then without this idea, your hurting of others is a lot less serious. Your shoe should be taken for stealing John's shoe, that is all.
You can hurt an innocent person. Or think that you have. What if God in fact let that happen for he sees some secret evil that is bad enough for the person to deserve to be hurt? If I have the right to say that God has a good plan despite the disaster all around me and no matter how bad it is then I have the right to say that if God lets me hurt somebody that person is not innocent no matter how much it seems they are.
If that makes you suspicious of justice administrators it gets worse.
Justice affects more than any one individual. It can be just for him to go to jail but unjust how his family are left to cope without him. They are probably the ones that are the worst off. So it is not simple. Nobody suggests that you should get a longer punishment for forcing the law to deal with you and leaving your family to suffer. Justice is an unclear thing and no one in religion or the legal profession likes to be blunt about that.
If we just want a person punished for behaviour we do not like that is not justice. It has to be really wrong in the first place. And what is condemning it about anyway? It is just about saying a person did bad - about an opinion and an evaluation. It is not going to undo what they did. It is not going to stop them doing it again. All it does is allow somebody else to judge so they can feel they haven't done this wrong deed and feel smug about that.
Religious persons say a law banning something has to punish or it is not a serious or real law at all. They add that the act calls out for punishment no matter how much the perpetrator wishes otherwise. But it says there could be reasons why punishment is not possible or cannot be done. So all we are left is with "You should not have done x". We don't have to affirm a God because some people want to moralise! God is really just a tool for people like that. No wonder they are so offended if you insult him for this is about them, their egos.
Human nature will only murder or do whatever harm it can think of for some good. St Thomas Aquinas said the reason this is evil for you are choosing what seems good without caring if it is really good or not. But that calls an evil act a mistake and a risk. Morality says to give the benefit of the doubt which leaves you that you have an impossible time explaining how and why you should punish somebody. He says that we are evil if we do something such as stealing or vandalising or wishing harm on somebody when we know that there could be bad results that otherwise would not come about. "When a man foresees that many evils may follow from his action, and yet does not desist therefrom, this shows his will to be all the more inordinate". He is clear that an evil deed cannot be made good by good results or a good deed made evil by bad results.
Interestingly, we worry more about a person being malicious than them being a thief or charming fraudster. According to Thomas, we know that to have a lying heart will lead to us hiding from ourselves the malice we may feel. So while theft is not malevolent, it is indirectly malevolent for your heart is letting evils in, including malice. To let the potential for malignant hate in is to be as bad as an actual hater.
If these doctrines of his are wrong then he is to blame for suggesting and programming people to become evil. We would expect to be complete monsters if we could live to 200. We just don't live long enough for the full horrors to show up.
Believers are saying that if there is no God to make justice real or valuable or workable, then any punishment from society is illicit for no God authorised it to administer it. So you should be exonerated by society and recognised as exonerated and yet they inflict punishment on you.
Now an all-good God has the power to exonerate, or nearly completely-exonerate, so God or not it makes no difference. One way this could be done if there was a universe in which there were beings so big and vast that their good work is immeasurably bigger than any wrong we do who could offer penance for us.
People bemoan those who they see as evil monsters getting exonerated when it is others who have to deal with them. They in fact don’t do much to bring the dangerous people they can deal with themselves down. They like to be armchair judges. And it is very one-sided. Those who want monsters not to be exonerated come across as hypocritical for they do not consider the other side. A Hitler being dead should mean good things coming to his living victims proportionally. But they don't even care or help. They just want him dead.
Why would most people let a Hitler take power? Why would they look the other way when atrocities start happening? It is frightening especially when they say they abhor what he stands for. So what do they actually want? Do they want somebody else to bring him down for them when they could do it themselves?
For many it is something else. It is about wanting God or fate to attack the likes of Hitler. They want the supernatural or magic to obliterate him. They hope some amazing coincidence despite all the odds will remove him. That is an excuse for not getting involved.
And Hitler was exonerated for he didn't suffer and escaped human justice. And if God is merciful that means repentance or not, Hitler was not in his clear right mind when he died and so would have been welcomed into Heaven probably after cleansing in Purgatory. It is a testament to hypocrisy that no Pope or anybody in religion dares say publically that they hope he is in Heaven.
If Hitler is punished after death what good is that? It does not take away anybody's crave to see him get away his comeuppance for they know nothing about it. It is a fact that the anti-exoneration fantasists cannot be satisfied with any tyrant's fate. Their thirst has to get worse and worse. It will be taken out on neighbours, the dog, politicians and on family.
FINALLY
Some might then say, "No matter what you do, good or bad, it is irrelevant if there is no God. Helping a baby out of a pool or holding her down is no more moral than a tree falling beside you or on you."
But good and bad could exist and still be irrelevant. They do not matter under the circumstances. If human nature pushes God out so that the universe is the same as it would be if there is no God then believers and atheists are on a level field.
Our point is that God or not, you cannot prove that what you do matters much.
Believers want morality to be relevant and practical and for people to preach it for they feel protected by that. It is still foolish to think, "I need morality therefore it matters."
Believers argue that you need God in order to truly recognise morality as what it is. They enunciate, "Atheists may be moral yes but they have no real reason to be. Only God can explain or show why we should be moral." That accuses the atheist of being incoherent. The atheist in turn accuses God believers of being incoherent on morality. They will point to how things such as the trolley problem, the suffering of babies, the cruelty commanded by God in the Bible, show that those people do not agree with their own standards.
Both need to unite in affirming that God belief is irrelevant to showing morality is any good to us.
The exoneration argument is over-simplified and deliberately so. It is useful for portraying atheists as going to wreck social cohesion.