Which school of thought's motto is: "Life is belief and struggle"?

This sentence is half a line from a poem by the Poet Laureate Ahmed Shawqi. The first half of the line is: "Stand by your opinion in life as a struggler, for life is a creed and a struggle." It has been mentioned by a number of scholars in their books, such as Sheikh Abdul Aziz Al-Salman and Sheikh Ali Al-Qarni.