Baselessly? You mean that my logic is flawed? Please tell me where.
Your logic is flawed as it assumes that the Bible is literal, and factual. This means that one must than accept that God exists; however, you're an atheist. So you are applying a standard on the Bible that you don't even accept. And the whole reason is to just make a claim based on your preconceived ideas.
At the same time, you add ideas to the Bible that simply never appeared in the Bible, such as the character of Satan (at least for the OT, in which these atrocious acts occurred).
Apparently you have done the research, so why is it ridiculous?
It is ridiculous as one, Satan never killed anyone in the Bible. Satan didn't even exist. During the NT period, there becomes an idea of Satan (one could call this a proto-Satan), but even then, there is never murder on Satan's part.
Second, it assumes that the Bible is literal, which is an idea that has been rejected for most of history. Looking at early Jewish interpreters, such as Philo, as well as early Christian interpreters, such as Augustine, recognized that the Bible was not 100% literal. It really has only been in the last 100 years or so that Biblical literalism really took off. And even then, it has largely been a minority. Not to mention that mainstream scholarship, both Christian and Jewish, as well as mainstream seminaries, and churches accept that there are problems with the Bible. Many have also now rejected the idea of an actual figure of Satan.
Third, it tries to force a single idea on all of Christianity, when that is usually not possible. It ignores that vast differences in theological approaches and interpretations.
Characterize it however you wish, but the implication still stands, Satan got his way: there's evil in the world; and god didn't get his way: There's evil in the world.
Why must evil being in the world come from Satan? A figure that has largely been ignored in Judaism and much of Christianity? There being evil in the world doesn't mean that Satan (a figure that really isn't mentioned in the Bible) got its way, and that God didn't get its way.
Instead, as many theologians and Christians accept (especially in process and liberation theologies) is that God is limited. That in the beginning, God allowed chaos to exist, as from chaos, creativity can be had. Also, in order for humans to be humans, God could control humans. This chaos leads to what is deemed to be evil. However, many accept that it, the chaos, was good anyway.
There is evil in the world, that does not mean that God didn't get God's way, and that some other entity won out. It simply means there is evil in the world.
So, what do these Christians contend; Satan didn't get his way: there's no evil in the world; and god did get his way: There's no evil in the world?
That Satan does not exist.
Not accepted by whom? From almost all Christians I've heard speak to the topic they readily concede that god killed people.
Just because you have talked to some Christians hardly means anything.