Though not directly stated, Paul essentially describes what happened to Abraham at his calling and must happen to us. Abraham's mind—and therefore his life—was so arrested and redirected by God's revelation of Himself that he responded dramatically, despite the realization that he could no longer live as he had for 70 years. He had to make changes, and some of them would be considerable and costly.
He could no longer live completely for himself. He no longer perceived people as he had all his life. He especially could no longer perceive his new God and Savior as He formerly had. A new man was being created from within, so he had to make a clean and permanent break from his old life. His life now had a new Object toward which he must walk. His life had a new direction, a new relationship, new desires, and new requirements to fulfill.
We must never forget that Abraham was a special case; he is the prototype who set a vivid, overall example for all his spiritual children to follow to some degree. There were bumps along the way; at times, he fell short of the ideal. Yet, on the whole, he did nothing less than set a superb example for all of us.