Answer:
In his most controversial speech titled "Beyond Vietnam" Martin included the quote of a Buddhist Leader to let his audience know that the US is on the verge of being called a nation of violence and militarism rather than of freedom and democracy. The possible effect of including this quote was to persuade his audience of his credibility.
Step-by-step explanation:
"Beyond Vietnam" was a speech delivered by Martin Luther King Jr. on April 4, 1967, at Riverside Church.
The speech was delivered to address the problems of the Vietnam War and its side-effects not only on Vietnam but the poor of America as well. In lines 297-303, King included the quote of a Buddhist Leader to give an insight to his audience about what the Vietnamese are perceiving about America. America has been considered a nation of peace, freedom, and democracy but that image was on the verge of being spoilt by the War.
So, the possible effect of including this quote would have been to persuade his audience and assure the credibility of his speech that what he is saying is true.