A difference between theism and atheism is each's idea of morality. To the theist, whether Jew, Christian, or Muslim, morality is linked to obedience to alleged divine commands. A theist conforms to God's commands whether they call for proselyting or committing acts of murder and genocide. So the theist believes morality is linked to obeying God without question or deliberation.
The atheist, however, bases morality on doing what's right based on reasoning and determination on their own initiative without regard to divine commands and promised rewards. The atheist simply does what is right because it is right, not because he/she fears of punishment in an eternal afterlife of torment.
There are a lot of simply atrocious commands found in the Old Testament, and atrocious doctrines found in the New Testament. You don't have to take my word for it, just grab a Bible and carefully and rationally read it. For example, God thought it moral to destroy all life with the exception of eight souls in a monstrous deluge. All the innocent toddlers and babies yet unborn, and the aged with their wisdom, and innocent animals and plants wiped out and destroyed . Theists will say that whatever God declares moral is moral and right because God is soverign. What about conquering Canaan through repeated incidents of genocide, and ripping pregnant women open with a sword and slaughtering the unborn children ? What about taking underage sex slaves ? What about the sacrifice of one's daughter as a burnt offering, or Abraham's willingness to murder his son at the command of God ? And that's just the Old Testament.
Jesus is presented in the Bible as the Son of God, and considered by many people, even atheists, to have been the greatest moral teacher of all time. None of Jesus' teachings are unique to him. Every one of his moral precepts can be found in the Old Testament and other Jewish writings on the laws of the Torah. And some of his moral precepts predate him by hundreds of years in other religions and philosophies.
Jesus, however, introduced an idea that the Torah did not contain. In the Torah God's punishment was limited to this life. But Jesus introduced the doctrine of hell for those who neither believe upon him nor obey him. Jesus extended punishment to eternity. This is a form of fear induced coercion into unthinking obedience. The nicest, kindness, most generous unbeliever will go to eternal torment after death after a lifetime of goodness, but a man who murdered hundreds of children could, at any time right up to his last moments in this life, repent of his sins and accept Jesus as Lord and Savior and go to heaven after a lifetime of the most reprehensible crimes.
Ask yourself honestly and objectively if any of these things mentioned can possibly be moral.
What would you do as a Christian if you learned begrudgingly but to your satisfaction that God definitely did not exist after your years of devotion ? Would you live a good life ? Would you lose all reason for morality and begin to engage in crime and anarchy ? If so you were never moral to begin with, your morality was based on your beliefs about God, in other words they didn't originate from you. They were imposed upon you from the outside under threat of eternal punishment, and thus are artificial morals.
An atheist's morals come from within themselves, based upon their reason and understanding of human needs. They don't do good things for hope of reward or fear of punishment, and most atheists definitely are good people and do good things. Atheists already are certain that no God exists, yet they do not behave as moral monsters.
Atheists are perceived by many religions to be immoral debauches, thieves, liars, murderers, kidnappers, rapists, child molesters, etc. Granted there are some immoral atheists, some atheists can even be sociopaths, but so are a great many theists who engage in these immoral atrocities, and Jews, Christians, and Muslims are not guiltless, not in the early history of the Synagogue, Church, or Mosque, and not now. So just what is the difference between the theist and the atheist ? They both possess a percentage of good atheists and bad atheists and good theists and bad theists. The only difference between them is theists believe in a God and unquestioning divine sanctions disobedience of which leads to eternal damnation and uncritically obeying regardless of whether the act is morally right or wrong in an effort to cleanse the world of evil opens the way to salvation and paradise.
Atheists, however, do not possess belief in a God. They believe that nature is all there is, and they can present evidence that man has evolved to utilize the mental faculty of reason that he has come to possess. The atheist uses reason to work out what is the right thing to do and then goes about doing it. And he/she does so only because they believe it is the moral thing to do without regard to any divine threat designed to coerce belief and conformity.
This shows that atheist morality is more evolved than theist ideas of morality. So in my estimation atheism has the better system of morality. Atheists do the good they do simply because it is the moral thing.