Creation? Just by saying God created humans with a lower nature, to me, right there, makes him responsible.
Why would that make God responsible? God gave man a brain and free will to choose between our two natures. God does not influence our choices so God is not responsible for them.
Christians had the same problem trying to explain evil.
Baha'is don;t have any problem explaining evil. It is right there in black and white in the Writings of Baha'u'llah.
“God hath in that Book, and by His behest, decreed as lawful whatsoever He hath pleased to decree, and hath, through the power of His sovereign might, forbidden whatsoever He elected to forbid. To this testifieth the text of that Book. Will ye not bear witness? Men, however, have wittingly broken His law. Is such a behavior to be attributed to God, or to their proper selves? Be fair in your judgment. Every good thing is of God, and every evil thing is from yourselves. Will ye not comprehend? This same truth hath been revealed in all the Scriptures, if ye be of them that understand.” Gleanings From the Writings of Bahá’u’lláh, pp. 149-150
They came up with Satan and Adam and Eve disobeying God. Then God cursed them and the Earth. But Baha'is don't have those things to use as reasons.
Baha'is know the reason. See above.
Baha'is have man, from the start having two natures. If they were designed and created that way, then what should we expect? Some of them, or most of them, will choose their lower nature.
What should we expect? If they are going to obey God we expect them to follow the teachings and laws of God in which case they would follow their spiritual nature. If they choose to turn away from God we would expect them to follow their lower material nature. It's a choice.
And did God know they'd do that? Yes. Some of us blame God for designing people that way... you don't. Fine.
It is illogical to blame God for the choices people make and try to deflect by saying we have no free will. If we had no free will we could nit make any choices at all, good or bad, so that plane won't fly. It won't even get off the runway. It is just an excuse, a way to blame God for what humans are responsible for, their moral choices.
But why there is evil and pain and suffering in the world is always going to be something that people will question religious people about... Why does their concept of God create it and why does he allow it. All religions give their reasons... none of them are all that convincing.
Why shouldn't God allow it? Why should God stop the evil on the world? This is always going to be something that religious people will question atheists about. Why should God stop people from doing evil when people have the free will to choose and stop themselves from doing evil? To say that God is omnipotent so God can do anything is not an answer. God is not responsible for what humans choose to do and God is not responsible to stop humans from doing what they do.
Why there is pain and suffering in the world that is not the result of free will choices people make is another conversation, something that people should question.
“Some things are subject to the free will of man, such as justice, equity, tyranny and injustice, in other words, good and evil actions; it is evident and clear that these actions are, for the most part, left to the will of man. But there are certain things to which man is forced and compelled, such as sleep, death, sickness, decline of power, injuries and misfortunes; these are not subject to the will of man, and he is not responsible for them, for he is compelled to endure them. But in the choice of good and bad actions he is free, and he commits them according to his own will.” Some Answered Questions, p. 248
Man is compelled to endure their fate because God set it up that way, and I do question why it had to be this way, although there is no answer that is completely satisfactory.