I would ask your sister why she loves a god who wants to murder you for the mere crime of not kissing His ass. Why would she worship someone so heartless and cruel? If she loves you, and she loves Him, then why would He murder someone she loves? How can she have a shred of respect for the person that wants to murder her brother. And if she were God, would she honestly do the same?
Furthermore, where does the Bible say you're going to be destroyed? All I've ever heard on the subject is that, only AFTER all the obvious signs of Armageddon, when God has proven His existence to the entire world, if you choose to "take the mark" i.e. follow Satan, only THEN will you be destroyed. After all, it wouldn't be fair to all the atheists and believers in other gods and mentally handicapped people and primitive tribes all over the world who cannot be blamed for their beliefs, or lack thereof, for God to straight up murder them at Armageddon without first proving Himself to them and giving them the chance to choose His side.
Oh, and if that's not enough, ask her why she thinks she's above Jesus, who chose to dine with sinners because "healthy people have no need of doctors," and who washed the feet of His disciples. If He can humble Himself and extend that much compassion to others, then your sister is pretty much required to do the same. Aren't we all expected to follow Jesus' example?