And Jesus said that the person without sin should cast the first stone. I do not know who that might be because the Bible also says everyone has sinned. So do your best to take care for your own sins and let God do the punishing of those who need it. And again, I am talking about the 10 commandments only. Many of the ceremonial laws were in fact eliminated because there is no temple or priesthood today.
Now you're quoting Jesus when it suits your argument. Then you say "the Bible says..." Yes, the Bible does say that... somewhere, great. But, it is the Bible that says which sins deserve death and how the person that committed the sin should be killed. So in reality, we don't believe or follow everything... just because the "Bible says so."
Does a good Christian believe everything Jesus says? Of course, at least they probably say they do. But, I wonder, how many Christians commit adultery in their hearts? I imagine a lot of them. Should they obey what Jesus told them they should do? No. Even if they did pluck out their eye, would it stop them from lusting? I doubt it. So not everything Jesus said works in the real world. And, not everything he said should be taken literal, especially when we are counting on the writers to have had good sources or, if they were eye witnesses, to have had good memories.
So you say let "God do the punishing." Unfortunately, we do have people doing all sorts of evil things in the world. What should we do with them? Let them go free, because not one of us is "sinless"? I hope not. And don't forget, murder is part of the 10 Commandments, so what does the Bible say to do? And, what do we do with them in the real world? We let our judges condemn them to death or put them in prison. So no, we only follow whatever we like about the Bible and disregard the rest. Especially, if you're a Christian, the Jewish part of it.