"Christians are told not to judge."

Lewis is referencing a portion of Christ's Sermon on the Mount (Matthew 5-7) in which He says, "Judge not, that ye be not judged. For with what judgment ye judge, ye shall be judged: and with what measure ye mete, it shall be measured to you again" (Matthew 7:1-2, KJV).

Some Bible expositors interpret the statement differently than Lewis did, since it is impossible for people never to make a judgment call on anything, and since Christ goes on in the same passage to require believers to use discernment when judging ("Give not that which is holy unto the dogs, neither cast ye your pearls before swine, lest they trample them under their feet, and turn again and rend you," Matthew 7:6). In addition, in John 7:24 He commands His followers to "Judge not according to the appearance, but judge righteous judgment."

Other translations soften the seeming bluntness of Christ's statement in Matthew 7:1.

"Do not judge, or you too will be judged." (New International Version)

"Do not judge so that you will not be judged." (New American Standard)

"Do not judge and criticize and condemn others, so that you may not be judged and criticized and condemned yourselves." (Amplified Bible)