Christianity; the World's Most Violently Persecuted Religion

[Sheldon]

The very notion that Christianity is persecuted is laughable considering the biases in their favour.

I'm sorry you find the persecution of over 300 million people laughable; 

Is English not your first language, only that is not remotely what he said? 

do you think that maybe should be a red flag - say if I was to come here and start justifying the violent persecution of even 10 atheists, started saying it's "laughable" when I hear those atheists are being sold into sex slavery or used as child soldiers after their parents are killed?

I'll try bullet points then:
1. The poster did not say, nor did they remotely imply, that persecution of any demographic was laughable.
2. The poster clearly said, that the notion that Christianity is persecuted was laughable. 
Those are two very different claims. However if someone were to say it was ok for a large demographic to be murdered through gun violence say, then yes that would red flag that person as bigoted, and amoral, or even immoral, give the largest percentage of that demographic was obviously made up African Americans, when they were protesting loudly at the death one rich white man, then this also would be a red flag they were being fairly obviously racist. 
In case I am being too subtle here, that claim was yours, it was both bigoted and racist, and every time you've been called on it, the only response from you has been the risible "nuh uh, you are" argument, that most people will associate with infants. Not once have you recanted, clarified, apologised, or dissociated yourself from the racist nature of that claim. Had you done so, and explained it was ill-conceived rhetoric for example, others might not still be calling on you on your racist trope, about it being ok to let people in slums be killed through gun violence, and not all gun violence being equal. 
If this is too hard, try and imagine what you would call a claim that suggested a demographic of mainly black people, was of less value than a demographic of mainly white people.