Rav Kook was known for his boundless love for all Jews, even the evil ones. However, he was a balanced individual and understood that JUST loving is dangerous as it could lead to the adoption of the ways of the evildoers. I often hear people who will justify the ways of the sinners and discern that the talker himself is not so distant from their ways. Yes indeed, it is important to use our capacity for HATRED against reshaim. Of course there should also be an element of love and chesed that shine their great light on the souls of even the wicked, however the primary feeling should be one of hostility. This will ensure that we don't follow in their ways. The laissez faire attitude of "hey, everyone has free choice and that is the path they chose" it mortally dangerous for the soul. What guarantees the purity of the soul is a feeling of repulsion for evil people and their erring ways.
Please try to read and understand the following passage written by Rav Kook in Shmone Kvatzim, kovetz 1/473.
מי שחסר לו החוש של שנאת הרשעים יוכלו התכונות המעשים והדעות הרעות להדבק בו ולפגמו, ואף על פי שעל ידי גודל מיתוק של חסד הולך האור ונזרח גם על הרשעים, מכל מקום ראוי לאחוז במדה ידועה של גבורה, שהיא מכרת בשנאה פנימית לרשעים הגדולים, מרימי יד בתורה. ומדה זו היא כמו סנדל לנשמה, שלא תטנף רגליה ביון מצולות הקליפות, והיא משומרת ע"י תכונה זו בטהרתה
