What Biblical justifications are used for having separate denominations?

From my reading of the Bible, I have come to understand that unity among Christians is a good thing. 1 Corinthians 1:10-13 > Now I exhort you, brethren, by the name of our Lord Jesus Christ, that you all agree and that there be no divisions among you, but that you be made complete in the same mind and in the same judgment. For I have been informed concerning you, my brethren, by Chloe’s people, that there are quarrels among you. Now I mean this, that each one of you is saying, “I am of Paul,” and “I of Apollos,” and “I of Cephas,” and “I of Christ.” Has Christ been divided? Paul was not crucified for you, was he? Or were you baptized in the name of Paul? Psalm 133:1 > Behold, how good and how pleasant it is
For brothers to dwell together in unity! These, and other passages of scripture, seem to emphasize the importance of Christian unity and love while de-emphasizing the importance of distinctions. In light of these passages, how do Christians justify separating themselves into so many different denominations? Are there any Biblical justifications given for why having such division is preferred over unity?