The more we walk and talk with Jesus, the more we become like him.  I believe that's something Christ does IN us, resulting in the transformation of our hearts.  But it's still our choice to live that out in our actions. If all I do is rant and rave about injustice, but fail to extend mercy to others, I'm simply a "noisy gong" as mentioned in 1 Corinthians 13:1.  But when are actions match our words, it can make a difference in someone else's life who then might show mercy to another person.  I know that when I treat other people like I want to be treated, it has the potential of changing the world one person at a time.  And if nothing else, it changes my world.
I've known cynics who refused to vote or volunteer in a soup kitchen because, "What difference does it make?" Then someone did a random act of kindness for them that made their day, and I saw a spark of hope light their hearts that, just maybe, being generous DOES matter.  Then they passed that spark on to someone else.
I worked in the drive-through window at a Starbucks for eight years.  Several times a week, a customer would pull up and say, "I'd like to pay for the car behind me."  When the next car came to the window, I always said, "You have just been visited by the Coffee Fairy.  The person in front of you paid for your order just to do something nice for you.  You can repay them by doing something kind for someone else today."  Reactions ranged between shock and tears.  And frequently they said, "Well, I want to pay for the car behind me."  One time that first act of generousity was passed from person to person eight cars in a row.
Just one act of love, justice and kindness at a time CAN change our world.