In the context of historically Christian nations sexual things not approved by the bible were sin and associated with hell, demons, satan, judaism and such. Theres naturally stories about demons, or women, luring innocent Christians into having sex outside of marriage which is a sin, and you get strong association with sexual promiscuousness and succubi. Those stories then carry over into the realm of games.
Porn is obviously un-christian and subsequently culturally taboo and evil. Porn producers were inspired to use satanic imagery and words like "evil", "hell", "fallen angels" for their logos because thats what people expected.
Incidentally many porn producers are jews and most porn websites are ran by jews.