The love of God can best be expressed by the good works which we are doing to others. The message of the kingdom of God can be preached better by showing people the goodness of God. We should not preach about a good God when we ourselves cannot be good. Doing good works is the way to propagate the gospel of Jesus Christ.
The Bible calls us the lights of the world. The best way to shine our lights is by doing good to all men. The Bible says that we should let our lights to shine before men so that they might see our good works and glorify our Father who is in heaven.
Also, we are the salt of the earth. As the salt of the earth, we are those who should season the world. We are to make the world better. It is by our good works that we can make this world better.