Metropolitan Kallistos Ware argued the only thing God cannot do is force us to love Him voluntarily. Evil is the condition of not loving God; without the choice to love God voluntarily such love would be meaningless, ergo, free will naturally involves the condition of evil.
Isaiah531sMessiah, you should be aware that atheists will most frequently attack Christianity on grounds like this, which operate in a complex area of theology and apologetics known as Theodicy, an area focused on the question of “How could God allow this?” It’s a dangerous area for an amateur who is not familiar with apologetics and who has not studied the problem to try and debate; what is more, misconceptions about divine omnipotence, the nature of God and ultimately, the problem of evil, in short, misconceptions concerning Theodicy, lie at or near the heart of the belief systems of most Atheists; it is by obsessing on an erroneous conception of Theodicy that they lose their belief, or confirm their disbelief, in the existance of God or other deities.*
*I would further argue that the incompetent approach to the Theodicy question taken by non-Orthodox Christians, in particular, the gruesome Calvinist doctrine of double predestination/forordination to damnation, combined with the utter lack of satisfactory answers to this question by non-Christian religions like Islam, which drives intelligent people of conscience towards atheist humanism, and these people tend to have a very toxic outlook on religion as a whole, consequently. The best most of us can do for them is pray; it is unlikely you will be able to argue with them and successfully convince them of your faith in that manner; in Orthodoxy and Heterodoxy, Second Edition, by Fr. Andrew S. Damick, he points out the futility of trying to convert people through polemical argumentation.
