It’s true, according to the Bible anyways. If you are a Christian, you don’t judge non-Christians. If you consider yourself a Christian and you raise your voice about something like gay marriage, be careful that you’re not raising your voice against non-Christians who wish to marry. Marriage is not strictly a Christian institution.
- “What business is it of mine to judge those outside the church? Are you not to judge those inside? God will judge those outside. ‘Expel the wicked person from among you.'” ~ 1 Corinthians 5:12-13 NIV
For a little more Biblical context of where the Bible calls for judgement, check out the following link:
- Why does Paul judge when he tells us not to judge? (1 Cor 5:3; 4:5) http://bibleq.net/answer/110/
Christianity Simplified 
Don’t judge hypocritically =/= Don’t judge period
I agree with Soduhson. If we read what Christ said about judging, it’s about not judging with hypocrisy. A man with a plank in his eye should not try to remove a speck from another man’s eye, but after the plank is removed, he still assists his friend with the speck in his eye. I would say that judgement itself is not the end game. If people understand that they are sinners, and they understand that they will be judged as such before a perfect God then they understand why they need a savior. I would not run around telling everyone everything they were doing was wrong without explaining the whole picture.