We need not worry about this doctrine which was found unscriptural as early as Luke's time. If Jesus really came to be murdered and thus “to take away the sin of the world” (John 1:29), he would have used his superhuman skills to explain this incomprehensible teaching (killing the innocent removes the sins of the sinners). The only passing comment Jesus made on this is found in Mathew 20:25-28 which was ascertained by Luke as later adoption, hence Luke deleted the controversial verse (“son of man came to give his life as a ransom for many”) from his account. (Luke 22:25-27)
Even after the so called ransom was paid, sin continues to rule the world, and mankind continues to be under the slavery of sin for over 2000 years.