What does it mean to be created in image?

God made man in His image. He made him to be His own companion. God would not want a companion who was unlike Himself, and since He is Omnipotent, Omnipresent and Omniscient, He fills man with his own power and presence and wisdom, always provided that the individual chooses God and says— 

I have my one God-given eternal possession, my Godlike quality of free will—I lay it down voluntarily to do the perfect will of God.

When a man does that, he rises into a far greater degree of Godlikeness or becomes far more fit to be God's companion himself, thus fulfilling his own destiny.

—William James in Spirit