Why I believe Leonard Ravenhill said, "Just do nothing... that's all." is because to be damned, you don't need to be the most wicked person alive. All you need to do is to simply coast on without Jesus and you don't need to blaspheme Jesus or shake your fist at God, just coast on without Jesus. From the worst sinner to the most morally good person, without Jesus you're really on your way to the burning Hell.
The worst sin of all? It's best summarized as, "I'll do it my way." Many people think nothing is wrong with them. Worse, many who think they're righteous are living sinful lives. That's really it to go to Hell means you simply do nothing about your sinfulness and your need for salvation. Either way, all the unsaved people go to Hell regardless of how huge or how small their sins are. Laugh at the salvation message all you want lost sinner and you're going to be the biggest loser of all.