The analogy of an operating room, where radical surgery must be performed, is a most useful way to understand this Scripture. Most of us today would accept the notion that the whole body is worth more than any of its individual parts, and when we develop a cancerous tumor on eye, hand, or foot, we cast aside "the offending member" — with regret, of course; but we operate on the assumption that it is better to enter life without the diseased organ than not to live at all. If a troublesome organ hampers our life or threatens our very existence we eliminate it. We recognize the principle involved. When a gall bladder or appendix is so badly diseased that it gives us no peace, we cut it out. When a hand or foot is diseased beyond help, we are not loathe to amputate in order to save everything else. When a tumor is malignant and threatens to take our entire life away, we are not hesitant to say to the surgeon, "Cut it out!" It is far better to leave behind the tumor than to threaten one's whole existence. We understand the principle involved. 

And what is true in the physical realm, translates over into the spiritual realm. If there is something in our lives: some habit, some action, some attitude, that gets between us and God, we must "cut it out."