You are
K2.
I'm from a Muslim country, but practise no religion myself.
Pakistan, but mountains don't practise religion (as far as we know).
I have killed over eighty people.
From Wikipedia: "K2 is known as the Savage Mountain due to the extreme difficulty of ascent. It has the second-highest fatality rate among the eight thousanders, with around 300 successful summits and 77 fatalities; about one person dies on the mountain for every four who reach the summit."
I've never been convicted, not once even been to court.
It wouldn't fit in a court.
They would have no case against me, as I never lifted a finger.
Not a finger, only a rock.
You might think I'm the most ruthless there is, but I'm not even number one!
It's not the highest mountain in the world (second highest), nor apparently the most lethal to climb.
Feedback section
The tags were key here. Obviously the first impression (that it referred to a murderous person) was going to be incorrect, but the geography tag cued me into thinking of physical geographical features, and the last line made me think of rankings (largest, tallest, longest, etc.) Once I knew I was looking for a near-record-breaking geographical feature which is known for causing a lot of people's deaths, the answer became easy.