"La Ilaha IllAllah Muhammadur Rasulullah"
The Muslim is not one who is named after his prophet. Unlike the other religions. Judaism is named after Judah who was the father of the Jews. Buddhism is named after Buddha who was the father of that religion. Christianity is named after Christ who they claimed was the son of God. But Islam is unique in it does not call to a personality. It calls to a concept. And that concept is "La Ilaha IllAllah"
Once that concept is in vibed in the human heart it becomes more than a concept. It becomes a reality by which the human being is able to walk on the earth as khalifah of Allah SWT and nothing less.
And yet that "La Ilaha IllAllah" can never be separated by the fact that it was brought by a human being. And because of that Allah SWT has made a second part to this message. And that message is "Muhammadur Rasulullah". It is not a call to the prophet Muhammad SAW but it is a recognition that human beings are guided to their Lord through human beings that are chosen by their Lord to guide them.
And because they are chosen, because they are "mustafa" we are commanded to show them great honour and great respect. To honour them by following them and to honour them by praising them and to honour them by carrying their message to others. So we do not call to the personality of our beloved prophet Muhammad SAW. But we call to his reality as the greatest slave of Allah SWT, Abdullah Wa Rosuluhu.
And this is what we call to because he is the exemplar. You have in the messenger of Allah the greatest example for those who desire their Lord, who hope for their Lord.