Verse 11 continues - "He who speaks evil of a brother and judges his brother, speaks evil of the law and judges the law. But if you judge the law, you are not a doer of the law but a judge." To judge a brother in this sense means to condemn him. It is not our place to condemn others, though we certainly have the responsibility to correct them, in a proper spirit, when it is necessary (Gal. 6:1). God's law for man today includes the command to love our neighbors as ourselves. If we speak evil of others and condemn them, then we are not practicing the law of love! Our Christian brethren are also our neighbors, and, if we hate them, we're essentially declaring that this law of love is not worthy of being obeyed! Thus, such a one is not a doer of the law but a judge of it! Anytime we know God's law and do not obey it, we're sending the message to Him that we view His laws as defective and, we don't need to live by them! To send that message to God is dangerous, as 4:12 implies.
"There is one Lawgiver [and Judge, SRB], who is able to save and to destroy." This is an obvious reference to Jesus the Christ. He is the head of the church. He is the preeminent one. He has all authority (Col. 1:18; Matt. 28:18). He is the only one qualified to serve in the capacity as both a lawgiver and judge. No mortal man has the right to make laws for deity or to judge God's servants, regardless of his righteousness, intelligence, experience, wisdom, or age! And that's why James asked the question - "Who are you to judge another?" We are so weak and ignorant in so many ways. What right do we have to be so presumptuous as to pretend to be God and condemn each other?
Now friends, please do not misunderstand, and please make sure you don't misuse this passage. James is not forbidding all kinds of judging (cf. John 7:24 and our archived lesson from June 25, 2005 entitled "Judge With Righteous Judgment"). A Christian must judge right and wrong based on God's word, not his own personal likes and dislikes. A Christian must not judge his brethren (or anyone else) out of hatred, pride, or jealousy but with a genuine desire to help.
Followers of Christ, remember that it is your job to serve the Lord and submit to Him, not to be a critic or a judge! How can brethren be close like family if they are constantly looking to criticize and find fault with each other? We cannot have a wrong attitude toward a brother in Christ and be right with God (cf. I John 4:20,21). We should be looking for ways to compliment and encourage each other as much as possible. Yes, I realize that sometimes rebukes are needed (II Tim. 4:2), but let's make sure rebukes are given because we love the person, not because we want to tear them apart and get our own way!