And this is love, that we walk according to his commandments; this is the commandment, just as you have heard from the beginning, so that you should walk in it.
2 John 1:6, ESV
Sometimes you have to be mean in order to love God and obey his commandments. They seem to be one in the same.
The meanness you have to do is stated a couple verses later:
If anyone comes to you and does not bring this teaching, do not receive him into your house or give him any greeting, for whoever greets him takes part in his wicked works.