It was put forward by Father Didong, the dean of a French monastery.

..... On the issue of determining the Olympic slogan, Coubertin initially thought that the slogan of "unity, friendship and peace" should be used to guide the competition. Later, one of his friends, Father Didong, put forward the slogan of "Faster, Higher and Stronger", which was appreciated by Coubertin. He believes that it embodies the great spirit of mankind's eternal upward and continuous progress, and later advocates it as the slogan of the international Olympic Games. ...