Summary: The Word cautions Christians against a judgemental attitude. When we imagine that we are judging others--even those we identify as "wicked sinners," we expose ourselves to the very judgements we pronounce.
“You have no excuse, O man, every one of you who judges. For in passing judgment on another you condemn yourself, because you, the judge, practice the very same things. We know that the judgment of God rightly falls on those who practice such things.” 
“We know” is an expression used frequently throughout the New Testament. Whenever a reader sees this expression introducing a concept, it is as though the writer is waving a brightly coloured flag; with this literary device, the writer is emphasising a truth that the reader must not ignore. “We know” stresses that what the writer is about to say is a certainty; there can be no appeal because the truth is certain and self-evident. Over the coming weeks we will explore a number of these certainties delivered by the various writers of the Word. These certainties comprise a powerful, practical theology.
Today, I am focusing on quite a stern statement from the pen of the Apostle to the Gentiles. It is almost as though he was rebuking fellow Christians for being judgemental. We might be confused by such a forceful warning, especially in light of what preceded this particular portion of the Letter to Roman Christians.
Jesus had some cautionary words concerning this business of judging. One of His statements seem to have become the life verse for people who knowingly act contrary to the will of God. In the Sermon on the Mount, Jesus warned, “Judge not, that you be not judged. For with the judgment you pronounce you will be judged, and with the measure you use it will be measured to you” [MATTHEW 7:1, 2]. Many rebellious people have memorised the first statement delivered by this divine warning, though few are able to quote the rationale behind the warning.
Perhaps we would be well advised to hear a cautionary statement which the Master delivered on another occasion. At that time, Jesus questioned those who were listening to Him, “Why do you not judge for yourselves what is right” [LUKE 12:57]? The answer implied is that people are caught up with their own arrogance or perhaps held fast in the grip of vengeance.
When some religious leaders were enraged because Jesus had healed on the Sabbath, their rage was exacerbated because He was teaching in the Temple; they incited a crowd by muttering against Him. As was His habit, Jesus confronted their rage in quite a direct fashion. Jesus warned, “Do not judge by appearances, but judge with right judgment” [JOHN 7:24]. Clearly, Jesus was cautioning that if you do not have the whole story, avoid judging another.
The darkest statement concerning judging must be one delivered as Jesus was nearing His passion. “Whoever believes in me, believes not in me but in him who sent me. And whoever sees me sees him who sent me. I have come into the world as light, so that whoever believes in me may not remain in darkness. If anyone hears my words and does not keep them, I do not judge him; for I did not come to judge the world but to save the world. The one who rejects me and does not receive my words has a judge; the word that I have spoken will judge him on the last day. For I have not spoken on my own authority, but the Father who sent me has himself given me a commandment—what to say and what to speak. And I know that his commandment is eternal life. What I say, therefore, I say as the Father has told me” [JOHN 12:44-50]. Hear what the Master said! Life and pleasing God hang on His words!