…But real trouble and woe arise when this invades spiritual affairs and when the devil plants his seed in Christ’s kingdom, so that it takes root both in doctrine and in life. The result in the area of doctrine is this: Although a man may have the assignment and commission from God to preach the Gospel, others arise, even among his pupils, who claim to know it ten times as well as he does. Thus it is the plague and misfortune of the Gospel to have everyone judging it, becoming a doctor of it on his own, and presuming to be a master in doctrine. This is what happened to Moses, when Korah and his mob rebelled against him and said (Num. 16:3): “Why do you exalt yourselves above the people of God? Are they not all holy? Shall God speak only through Moses and Aaron?” And nowadays they say: “Do we not have as much right to have the Spirit and to understand Scripture as others do?” Right away a different doctrine is served up, and sects are started. Then the judging and the criticizing begin, and particularly the shameful slandering, one party venomously accusing and misrepresenting the other, as we are experiencing right now. This brings on the deadly damage of dividing Christendom and undermining pure doctrine everywhere.  (Luther’s Works, v. 21, pages 211-212).

Matthew 7:1. Judge not, that you be not judged.  2. For with the judgment you pronounce you will be judged, and the measure you give will be the measure you get.

…To keep this sermon from becoming a stumbling block and being misunderstood as if it forbade any judgment or criticism at all, it should be clear, on the basis of what has already been said so often, that here Christ is preaching only to His disciples. He is not talking at all about the judgment or punishment that takes place in the world. In the household, for example, the mother and father have to judge among the children and the servants, have to administer punishment, even corporal punishment, when they refuse to behave. If a prince or a judge wants to administer his office properly, he cannot avoid judging and punishing. This is all part of the secular realm, which is not our concern here and which we will therefore permit to act the way it should and must act. What we are discussing here is another kingdom, one which in no way weakens or annuls the other, namely, spiritual life and existence among Christians, where it is forbidden for one to judge and condemn another. The devil always mixes into such judging to do his work. He gives each individual a high estimate of himself and the opinion that his cause must be the best and must be the only one to prevail, while he criticizes and undermines whatever does not measure up to his standards.  (Luther’s Works, v. 21, pages 210-211).