Any sin which is sometimes permitted will be abused.
Lying is one of them. One can change the truth for the sake of peace. Well, once you go down that slippery slope, you can fall all the way down.
One may get involved in Machloket for the sake of Hashem, which may include speaking L”H. The problem is, again, that once there is permission in a limited way, it doesn’t always stop there. (heard from Rav Frand)