My call to action should be pretty obvious.  I've been looking at some old conference talks and this is a theme that really stood out to me.  I used a serif font with the "leave the 99" because it helps show that being among the 99 is easy and can be comfortable.  I used tracking with that sentence as well to add emphasis that it takes action to leave the group in search of others.  I used weight, size and color to help the "one" to stand out as this is the whole reason we are out searching for those that need to be found.  I felt that the red color over the white snow showed the urgency of this situation to help convey the message that there are those out there that truly need us.