“If your right eye causes you to sin, tear it out and throw it away; it is better for you to lose one of your members than for your whole body to be thrown into hell.” (Matthew 5:29)
“The command to get rid of troublesome eyes, hands, and feet is an example of our Lord’s use of dramatic figures of speech. What he was advocating was not a literal physical self-maiming, but a ruthless moral self-denial. Not mutilation but mortification is the path of holiness he taught, and ‘mortification’ or ‘taking up the cross’ to follow Christ means to reject sinful practices so resolutely that we die to them or put them to death.
What does this involve in practice? Let me elaborate and so interpret Jesus’ teaching: ‘If your eyes cause you to sin because temptation comes to you through your eyes (objects you see), then pluck out your eyes. That is, don’t look! Behave as if you had actually plucked out your eyes and flung them away, and were now blind and so could not see the objects which previously caused you to sin. Again, if your hand or foot causes you to sin, because temptation come to you through your hands (things you do) or your feet (places you visit), then cut them off. That is: don’t do it! Don’t go! Behave as if you had actually cut off your hands and feet, and had flung them away, and were now crippled and so could not do the things or visit the places which previously cause you to sin.’ This is the meaning of ‘mortification’.
One wonder if there has ever been a generation in which this teaching of Jesus were more needed or more obvious applicable than our own, in which the river of filth (of pornographic literature and sex films) is in spate. Pornography is offensive to Christians (and indeed all healthy-minded people) first and foremost because it degrades women from human beings into sex objects, but also because it presents the eye of the beholder with unnatural sexual simulation. If we have a problem of sexual self mastery, and if nonetheless our feet take us to these films, our hands handle this literature, and our eyes feast on the pictures they offer to us, we are not only sinning but actually inviting disaster.” (John R.W. Stott, The Message of The Sermon on the Mount: Matthew 5-7 pgs.89-90)
“The eye is the lamp of the body. So, if your eye is sound, your whole body will be full of light; but if your eye is not sound, your whole body will be full of darkness. If then the light in you is darkness, how great is the darkness!” (Matthew 6:22-23)