...Poll: would you cut off one of your hands for spiritual reasons? For instance, to get closer to God?...
I probably would not do that. However, it is not necessary very easy question. For example, what would you do in the case that your hand is stuck in a machine that will kill you, if you don’t cut your hand off? By what I know, many people are willing to amputate legs or arms to stay alive. If there is afterlife and one would lose it, if he would not amputate, it would not be a bad choice.
If your right eye causes you to stumble, pluck it out and throw it away from you. For it is more profitable for you that one of your members should perish, than for your whole body to be cast into Gehenna. If your right hand causes you to stumble, cut it off, and throw it away from you: for it is profitable for you that one of your members should perish, and not your whole body be thrown into Gehenna.
Matt. 5:29-30
And obviously, if there is no afterlife, then that is a quite poor choice. Luckily I think there is always better way to avoid Gehenna (hell).