Am I the only one who feels this way about the Old Testament?

[Lexii, harbinger of chaos and sexual anarchy]

I’ve never read the Old Testament, let alone the whole Bible, in its entirety. Even so, it’s impossible for me to read it and not want to literally slap God in the face for murdering all of those people and what not.

No, you're not the only one. This idea is as old as the New Testament itself, Marcion, e.g., believed around the year 140 BC that the wrathful Hebrew God was a separate and lower entity than the all-forgiving God of the New Testament.

[Lexii, harbinger of chaos and sexual anarchy]

I have seen believer and non-believer alike make one God into two separate parts. This notion is as strange as it is illogical, and as illogical as it is un-Biblical.

Is that any more illogical than the orthodox Christian position which makes God into three separate parts and has one third killed by another third?

That's modalism Patrick!

More seriously though, what you are describing is not what Christians confess in the Nicene Creed.

It's not what's not on the Creeds, but I'd safely bet that most Christians are actually modalists, despite them reciting the creed