You say that like there's something bad about Communism.
This. However, it's an argument for another time and place.
Basically as far as I'm concerned the combination of 'fairy man in sky offering excuse' and the things said fairy man excuses leads people to bash Amarr in particular.
I find it amazing that so many seemingly anti-slavery like players end up joining factions like the Angels and Nation. I know there are several players who were in many ways anti-slavery and later ended up joining factions that pretty much do the slavery thing too.
This I suspect is based on a combination of the above factors of 'your religion is evil' and 'slavery is bad, and you promote it' combined with the ever present 'pirates are cool'.
Because of this religious slaver Amarrians get a lot of flak, all the time, while piratical, slave-holding Angels and mind-raping Sansha slavers who represent the 'perceived utopia' (a 'good' goal) don't get quite as much.
Also, most of the reason for the hype against the Sansha recently is due – you guessed it; incursions. When the truth is slapped in your face on a daily basis suddenly everyone care, suddenly everyone ALLWAYS cared. Where is the lynching-mob to torch every Angel stronghold? No-where to be found, because Amarrians are slavers, Sansha are evil cyborg kidnappers, and the angels?
They are cool Jack Sparrow-like pirates – why give them a hard time, even when one can argue that the slaves worst off anywhere is the Angel ones and those of the Serpentis. (They have plenty too; free labor after all) Sansha slaves have no idea they are slaves, and what can't feel can't suffer, while in theory it's only the 'bad' Holders who miss-treat their slaves in the empire. All besides the point though.
I'd blame our modern 'pirates are cool' thing for shielding other slavers leading to help funnel all the anti-religion, anti-slavery rage onto the Amarr.
/end rant