I'm unsure what point you're trying to make here.
[postings] on the Internet against anything religious [would be] 'racist'.
If not racist, what word would you use for attacking someone on the basis of their religion alone? I would add though, that since religion isn't always overtly displayed, people tend to judge religion on outward appearance, such as skincolor.
"who has actually had a fatwa declared against him, and faced death threats as a result of his support for equal marriage – to fundamentalists."
It's good that you put this into quotes, because it's not in the original article.
How is this any different than calling Trump 'Hitler' or a 'Nazi'?
How is what any different, exactly? Are you trying to excuse one example of repulsive behaviour based on even more repulsive behaviour?