"Why do you look at the speck that is in your brother's eye, but do not notice the log that is in your own eye? "Or how can you say to your brother, 'Let me take the speck out of your eye,' and behold, the log is in your own eye? "You hypocrite, first take the log out of your own eye, and then you will see clearly to take the speck out of your brother's eye. (Matthew 7:3-5 NASB)
Recognize that Christ's teachings in the first five verses of Matthew 7 concern themselves primarily with self examination. The primary purpose of this verse is to call the believer to examine themselves. The vast difference between a speck and a log should not be overlooked. When you look at another person and you can see their sin you must realize that sin you see, not matter how heinous it is remains yet a speck in comparison to your own sin. If you examine yourself you will find sin more grievous in yourself than any sin you have ever seen in someone else. If you disagree with this you need to spend some time praying that the Lord would reveal to you your own sinfulness. Now, when you see a speck in someone else's eye, know that they too have far more sin than that speck which you see, nonetheless you are not qualified to deal with that speck considering the vast amount of sin that plagues you. Does this make sense? It is true that everyone has logs, and that the speck you see is nearly the tip of that log, but before dealing with the speck, deal with your log.
There is a loophole in this verse, and too many people jump through it too quickly. "...then you will see clearly to take the speck out of your brother's eye" this little section in a sense gives license to deal with your brothers sin, however to earn that license an immense amount of self examination and confession must occur. If indeed you begin to deal with your own log of sin, you will realize it is 10000 times the size of the speck of sin which you seek to remove from your brother's eye. The question is, at what point can you see clearly enough to deal with your brother's sin? The answer is, only when you have seen the enormity of your own sin and come to the realization that the speck you seek to deal with is virtually nothing in light of your own depravity. At that point, and only at that point, you can exercise true humility in dealing with the sin of another. Again, realize the thrust of this teaching is not so much to get your eyes clear enough so you can rightly judge... that is a small part of it, the thrust of this teaching is to examine yourself and see the enormity of your own sin.