Some of the Bible is metaphorical, and a lot of it is "pre-Jesus" law. The way it goes is that when Jesus was crucified on the cross and took the punishment for the world's sin, a new covenant was made. So for example, before His birth, the Jewish people (and many other groups of people in that time) had very specific laws and punishments for certain crimes. After Jesus was crucified, He effectively says "I've been punished so you won't have to be, should you choose to accept such a gift". So now, things like gouging out your eyes and such are not needed. If I know what you're referring to though (better to cut off members of the body then live with them after sinning with them), I believe that's more a metaphor. Jesus is describing that the damage of cutting off your arm is less then that of suffering the damage of sin on your soul. Of course since Jesus died on the cross, should you choose to accept that gift and live accordingly (actively trying NOT to -blam!- up), then you have little to worry about anyways since Jesus took the fall for your sins. And that's how that works.