Empathy, compassion, mercy, caring, etc are NOT sins.  However, support of evil is a sin.  If you wish well some whom you know is evil, going to do evil, etc, then that is a sin as you are then supporting the doing of evil.

Evil is something morally wrong, harmful, or destructive.  It is something that is not within God’s Will for us to do.  Scripture has many references to things that are “not of God”.

However, one can have compassion for someone evil because of many things such as the way they were brought up, their life experiences, or things of influence in their lives.  They are headed toward Hell and the Lake of Fire and that is sad.  Empathy is the ability to understand and share the feelings of another, but not necessarily to support or agree with such.