Well, that's actually a good place to start:
Can you explain to me what about you as a person, or what about your argument, should entitle you to say things like your line about the Old Testament? You delivered an off-topic feelgood line, and at best simply don't care about the implications. And what you said is the Hebrew Scriptures are "very much immoral, bad, wicked whatever way you read it", excluding even the Jews from finding a better way to read it.
And instead of adjusting your statement, you chose
indignance↗: "Ah ah stop right there sir. No one is 'going after' anyone at all." And you doubled and
tripled down↗.
But the question has more to do with why you won't write a better argument, or perhaps why your argument requires that kind of statement. Really, in discussing a particular iteration of Christianity, you interjected an off-topic broadside that actually hits Jews.
So, what makes you, or your cause, so special that you shouldn't need to worry about such things?
While there is certainly much range for discussion of the nature, function, and value of scripture, starting with such generalization as, "SCRIPTURE is clearly inhumane, backward and savage", within the context that "The OT is very much immoral, bad, wicked whatever way you read it", is not a reliable or rational framework. Even if we set aside the point about the Hebrew Scriptures in particular, your argument would preclude anthropological and historical readings that do not trade in such assessments as "immoral, bad, wicked". But in your particular application, you crosscut a discussion to drop a line hitting Jews.
So even if the answer is that the hit didn't occur to you when you said it, we come back to wondering what makes what you have to say so special that you shouldn't have to attend even this basic degree of rhetorical diligence.
And, in its way, you'll find that's not too dissimilar from some issues tied up in all this drama. More generally, though, it will always stand out as strange when people who are within range of the correct answer would pass it over in order to go take part in the bacchanal they criticize. See it happen enough, and eventually it's easy to accept that's probably the point.