You can't handle the truth without handling the love
There's been plenty written about the dangers of knowledge without love and of love without knowledge; to pick two dangers, according to St. Bernard of Clairvaux, the former puffs up and the latter goes astray.
But I think we can say something stronger: That, when speaking of God and the things of God, knowledge without love and love without knowledge are essentially immoral. Thus the abyssmal evil of the demons, which have an angelic knowledge of God yet do not love Him.
Thus also, albeit on a much different scale, the wickedness of those who habitually use their knowledge of Catholicism -- the Faith itself, or canon law, or current or past discipline or custom -- not to build up the Body of Christ, or even to build up Christ within themselves, but to forge weapons with which to attack, belittle, ridicule, and otherwise effect their hatred of others.
There's a paradox of sorts here. The union of knowledge and love is so close and inseparable, since they both come from and return to the One God, that those who have knowledge of Catholicism but don't have love don't in truth have knowledge of Catholicism. They know facts, but they don't know the Faith.
Anyone who speaks the truth without love is not speaking the truth of God, just as anyone who speaks of love without truth is not speaking of the love of God.