The Holy Spirit does not teach your mind to be critical of other minds, because He does not want you to teach your errors and LEARN THEM YOURSELVES. He would hardly be consistent if He allowed you to STRENGTHEN what you must learn to avoid. In the mind of the THINKER, then, He IS judgmental, but only in order to unify it so IT CAN perceive WITHOUT judgment. This 
enables the mind to TEACH without judgment and therefore learn to BE without judgment. The UNdoing is necessary only in YOUR mind, so that you cannot PROJECT it. God Himself has established what you can project with perfect safety. Therefore, the Holy Spirit’s third lesson is: Be vigilant ONLY for God and HIS Kingdom. 

This is a major step toward FUNDAMENTAL change. Yet it is still a lesson in thought REVERSAL, because it implies that there 
is something you must be vigilant AGAINST. It has advanced far from the first lesson which was PRIMARILY a reversal, and also 
from the second, which was essentially the identification of what is MORE desirable. This step, which follows from the second as the second does from the first, emphasizes the DICHOTOMY between 
the desirable and the UNdesirable. It therefore makes the ULTIMATE choice inevitable. But while the first step seems to INCREASE conflict, and the second still ENTAILS it to some extent, this one calls for CONSISTENT EFFORT AGAINST IT. 
Urtext ACIM excerpt T6H