People in sports love to talk about the G.O.A.T., greatest of all time, in a sport or at a position. They measure greatness by wins and by the things they do to help their teams win. I used to joke with the people at my previous church that I was the best (full time) Pastor they ever had. They would remind me that I was also the worst Pastor they ever had since I was the only Pastor they had ever had.
The Disciples argued among themselves about who would be the greatest in Jesus' kingdom. They wanted to be the top dog. Jesus redefined greatest as welcoming children, serving others, being humble. Jesus' idea of greatness and the world's are very different. Do you want to be great in the eyes of people or do you want to welcome children and serve others in Jesus' name?