Mark 9:43-50 - Cut it off!
So if I steal things with my hands am I really meant to chop them off? If I can't stop swearing should I cut out my tongue? If I stare at pornography should I gouge my eyes out or worse?
Actually, I think Jesus is advocating something even more radical than this! See, the problem is that chopping my hands off doesn't stop me being jealous of other people's property. Cutting my tongue out doesn't stop me hating people or losing my temper. And gouging my eyes out doesn't stop me lusting in my mind. In Matthew's account of this teaching he also recalls Jesus explaining that sinning in our thinking is as serious as sinning in our actions (Matthew 5:27-30). So a literal interpretation stops short of what Jesus is getting at here and doesn't really achieve anything because hacking our bodies up won't stop us sinning!
Jesus is tough on sin. He hates it because it destroys us and he wants us to be ruthlessly thorough in avoiding it. This is the point. He wants us to live life fully in relationship with him rather than be destroyed by sin. Temptation itself isn't sin - Jesus was tempted (Matthew 4:1-11) but if sin starts with temptation (James 1:13-15) then it's a good idea to avoid it wherever possible (2 Timothy 2:22, 1 Thessalonians 5:22, 1 Corinthians 6:18, James 4:7).
So in practical terms, it's about cutting off temptation wherever we can. If we're easily tempted by sports cars then maybe cycle a different way home that avoids the showrooms. If we're tempted to lose control of our words when we're angry, perhaps make a habit of walking away from heated conversations. If laziness is our issue, then why not ask a friend to commit to giving us a wake up call? Or if porn's our problem, get some free accountability software to remove the opportunity of ogling at stuff we shouldn't. If it's getting drunk then maybe don't hang out in pubs so much or keep alcohol in the house. Whatever it takes to help us avoid that which destroys us. So probably not self-mutilation! Thank goodness for that!