Completely committed, devoted, invested and engaged to a cause. To have no reserves about the decision you are making. To be willing to go anywhere, do anything and give up everything in order to achieve your goal by any means necessary.
Martin Luther King Jr. was sold out for the civil rights movement.
Michael Jordan was sold out to becoming a great basketball player.
Gandhi was sold out to his protest.
In order to win in the Olympics, you need to be sold out to training hard.
If you want to finish Med School, you need to be sold out in your internship.
The Apostle Paul was Sold Out in his missionary work