First of all, Christians are commanded to judge sin.
And sinners. My apologies to zahc for not bringing more convincing evidence before. I will do that now. Most are gleaned from the following web site, which also contains more scripture references to the point, as well as a pretty good discussion of what Christians ought NOT do with regard to judgment.
http://www.christianciv.com/Judge_Others.htmFirstly, there are Luke 17 and Matt 18, in which Christ tells us to rebuke our fellow Christians when they sin, and then if they will not repent, to excommunicate them. In Matt 7, he referred to this as helping a brother get the speck out his eye (after we get the plank out of ours). In Matt 10 and Luke 10, he sent people out (not just his twelve disciples, by the way) to spread the Gospel, and he told them to publicly rebuke those who would not receive them. So yes, while there are certain things Christ did that we probably shouldn't do, as individuals, judgment is not among them.
FWIW, when I said that Christians are commanded to "denounce wickedness," I wasn't speaking of judging particular people, but of Ephesians 5.11: “Do not participate in the unfruitful deeds of darkness, but rather expose them.” That's really no different than what a lot of secular people and groups are doing when it comes to human trafficking, or food deserts, or whatever the cause du jour.