Because, the god of the Bible says that it creates evil and Satan is just a part of creation.

He tricks them according to folklore, apart from that golden fiddle player Johnny and a few others like him. I'm not sure it's punishing them, just playing dirty. Don't know much about hell, I'm not a catholic, we were pretty much told that's it's just being shut out of heaven.

I always saw this as a bait-and-switch. Satan promises you happiness, wealth, and then he just screws you over. That's the metaphor I assumed was in use. The contrast is that god promises you and supposedly delivers ... I leave it to others to decide which is the greater evil, an empty promise followed, symbolically, by "bwah-ha-ha, sucker!" (Satan) or an empty promise followed by a demand that you continue to believe empty promises.

Because the bible saids so.

He doesn’t exist, like God he is a human construct. Anyway isn’t it God who is the one who is supposed to punish not Satan?

Because he follows the ways of the shadows(agents of chaos) from Babylon 5 while God is like the Vorlons(Lord of Order) from same program. Shadows also punished those who took their own way but didn't follow them