Other Greek scholars say that Krino means to call in question, conclude, decree, esteem, determine, think and sentence . An illustration might be a house in poor maintenance. We must be careful about judging without facts or beyond the obvious. The Pharisees were notorious for judging based on silly rules and traditions and not the Scriptures. Peter, Paul and John did a lot of judging the right way.
Every second epistle is a judgment on apostasy.
Paul did a lot of judging and evaluating when it came to false teachers. We are mandated to judge false doctrine. To find a balance between legalism and mysticism we must judge righteous judgment. We can judge the overt and gross sins mentioned later in verse 9. However our judgment must always be tempered with a desire to restore, not punish.