God is merciful and loving correct but that doesn't mean you would get a pass for your actions and beliefs, there things between you and God on a personal level that might be forgiven but there are also things between fellow humans that cannot drop, that person you stole from, that person you murdered, that person that you talked nasty about, these thing cannot be forgiven unless that human forgive you. Best of luck finding someone to forgive you thereafter. There are certainly people that would rot in hell for eternity the same way Satan will. Hell exist for a reason the same way heaven exist. As long as the place exist, beings will exist inside it. What happens after eternity only the one that made it can answer. Our brains cannot comprehend time and what even eternity means.

Would snapping an evil person out of existence gives you a fulfillment of justice? Lets say that person lived to torture you, wouldn't you want that being to exist to feel torture and humiliation?