Atheism – is a denial of God, and therefore a denial of the Supreme Absolute, as the source of truth and objective morality.
From this it follows that every man according to his atheism can create morality. And nobody has the right to him to impose their morality. Therefore, there is no objective good and evil, and maniac killer Chikatilo with his morality from the standpoint of atheism is no worse than the Nobel laureate Ginzburg with his humanistic morality.

“The total amount of suffering per year in the natural world is beyond all decent contemplation. During the minute that it takes me to compose this sentence, thousands of animals are being eaten alive, many others are running for their lives, whimpering with fear, others are slowly being devoured from within by rasping parasites, thousands of all kinds are dying of starvation, thirst, and disease. It must be so. If there ever is a time of plenty, this very fact will automatically lead to an increase in the population until the natural state of starvation and misery is restored. In a universe of electrons and selfish genes, blind physical forces and genetic replication, some people are going to get hurt, other people are going to get lucky, and you won’t find any rhyme or reason in it, nor any justice. The universe that we observe has precisely the properties we should expect if there is, at bottom, no design, no purpose, no evil, no good, nothing but pitiless indifference.”
Richard Dawkins, River Out of Eden: A Darwinian View of Life

This is bare theory.
In practice, the state produces its own laws to regulate the life of society, which are based on some standards, including moral. If morality is not taken into account, how the state could determine, for example, criminal penalties?
Here the question arises: whose moral principles should be the basis of the laws of the state?
Since all human beings with their morals are equal to each other, the winner or those who are  stronger and bolder, or those who are convinced of the truth of his morals rest of the population, or for some other reasons. In any case, the moral varies depending on certain phenomena. The moral of atheists – is subjective.  The majority of atheists is in accordance with it.
And if morality can vary and, under certain conditions, for example, can triumph morality Chikatilo, or communists, or Pol Pot, is it worth to gravitate toward the atheistic belief system? At this point everyone decides for himself. The only question is to convey to people not familiar with such matters, the true view of the atheistic morality and its effects.