I tortured my mind many years with unanswerable questions like this, before giving up on such masochism.
First of all, the whole idea of original sin presupposes a single original breeding pair, which is inconsistent with the observed genetic diversity of modern-day humans. There are too many gene variants for a bottleneck of 2 to have ever existed. You could do worse than read Prof. Jerry Coyne's post on this. Also, try to imagine the moral horrors and physical degeneracy of widespread incest between the sons and daughters of a single "founding pair" stranded on some island. Would there also be incest between generations, I wonder?
Then, the abrahamic narrative accuses the fictional single breeding pair of committing the ultimate sin of being curious about good and evil. Never mind that humans are by nature (or by God's design as you would have it) curious, and could not have gotten where they are without this feature. Also never mind that people seem to be born with innate pro-social inclinations (e.g.the abhorrence of violence).
So after "sinning" by following their natural calling, this God sentences the single breeding pair to the pains of working for a living and the labor of child birth. Never mind that the archaeological evidence, as well as common sense shows that all animals, including humans, have always had to struggle to survive. Also never mind that the pain of child birth is due to the large size of the human brain, which can barely fit the birth canal (which is why we are not born with fully formed brains and need so many years to mature).
But let's skip over the absurdities of the Genesis myth and go on to the nature of God. The question to ask is this: what kind of all-powerfull god would send tsunamis and earthquakes to kill hundreds of thousands of people in horrible pain? Could this God also not delay the scientists' effort to create the nuclear bomb by a few month to avoid the firestorms of Hiroshima and Nagasaki? Did he turn a blind ear to the Jews' (or the Rwandan's more recently) prayers when they were about to be murdered by a genocidal enemy? Does he ignore the prayers of the poor women who get raped and murdered by serial killer (couldn't he cause some bystander to notice the abduction and call the police -- would that be too much to ask of him)?
Of course, God did find time to help Moses slaughter the women and children of the Midianites (who had harbored the Jews for several years in their midst prior to this massacre). He could even stop the sun for a day to allow the Jews to win an even greater victory in an instance. So you see, it's not for lack of power.
Then the Jesus doctrine enters the abrahamic landscape. Apparently, in order to forgive us, God has to inflict (again) a horrendous torture on a human that also happens to be his son. Instead of just... forgiving us. Or changing the brain circuitry to make murder, rape etc less likely to occur (OK, his version 1.0 of man wasn't perfect, let's bring a bugfix release, without removing freewill).
The only way to have a personal God who actively intervenes in the natural world and still have innocent people suffer atrocities is to paint him as a bloodthirsty monster who enjoys torturing and instilling fears in his "creatures", and also really likes to hear their anguished prayers and their praises when he randomly withdraws his tortures. This doesn't sound to me like a perfect god, but like the primitive invention of a cruel race.
Oh yeah, what about Abraham "being asked" to kill his son? If somebody insisted today that they are hearing voices urging him to murder his offspring, we would intern the schizophrenic in psychiatric ward. But this being a few thousand years ago he became the founder of a powerful religion.
I ask you to judge your God character as you would judge any one of us who happened to gain power over a society (an all-powerful dictator). Would you characterize such a character as a sane, good person, or as a perverted psychopath that must be locked up for life?
Of course, I'm not saying that "God" is evil, I'm saying that the abrahamic portrayal of a fictional God is an outgrowth of a sick ancient society that tells us more about their shortcomings than about the nature of divinity. And if you accept that description and try to defend the undefensible, it says something about your psyche.