Muhammad Ali, one of the most famous athletes in American history and a convert to Islam in the 1960s, returned to the public spotlight Wednesday night to say that political leaders have a responsibility to foster understanding about his religion.
His comments came after Donald J. Trump, the leading Republican presidential candidate, stoked anti-Muslim sentiment in the United States by, among other things, suggesting that foreign Muslims be barred from traveling to the country. Mr. Trump has also questioned President Obama’s affirmation that Muslim Americans are some of the nation’s sports heroes.
In a statement delivered to NBC, Mr. Ali did not speak about Mr. Trump directly but addressed his message to “Presidential Candidates Proposing to Ban Muslim Immigration to the United States.”
“We as Muslims have to stand up to those who use Islam to advance their own personal agenda,” he said in the statement. “They have alienated many from learning about Islam.”
Mr. Ali, a former heavyweight champion who once gave Mr. Trump an award at a celebrity event, has defended Islam on a national stage for decades.
In February 1964, shortly after winning the title — and before fully converting and changing his name from Cassius Clay — Mr. Ali defended his choice to participate in the Black Muslim movement to reporters.
“I go to a Black Muslim meeting and what do I see? I see that there’s no smoking and no drinking and their women wear dresses down to the floor,” Mr. Ali said at the time. “And then I come out on the street and you tell me I shouldn’t go in there. Well, there must be something in there if you don’t want me to go in there.”
American Muslims have often faced bumpy paths in sports. Mr. Ali stoked enormous controversy in 1967 when he said he would refuse to serve in the Army because of his Muslim beliefs. His quote, “I ain’t got no quarrel with them Viet Cong,” became one of the most famous of the 1960s.
After his refusal to join the military he was stripped of the world heavyweight title and lost his boxing license in New York. He was sentenced to five years in jail and was vilified by many fans. “He became a Muslim in 1964 after defeating Sonny Liston for the title,” Morton Susman, a United States attorney, said at the time. “In my opinion, his trouble started with that—this tragedy and the loss of his title can be traced to that.”
Mr. Ali’s case went all the way to the Supreme Court, which in 1971 reversed his conviction and agreed that he was deserving of conscientious objector status. After three years out of the ring, he returned to fighting and eventually regained his belt.
The basketball player Mahmoud Abdul-Rauf was a flashpoint for controversy in 1996 when, playing for the Denver Nuggets, he declined to stand for the national anthem, citing American military aggression around the world. “You can’t be for God and for oppression,” he said. “It’s clear in the Koran, Islam is the only way. I don’t criticize those who stand, so don’t criticize me for sitting. I won’t waver from my decision.” After a brief suspension, he worked out a compromise where he would stand during the anthem but look downward and recite a Muslim prayer.
But Mr. Ali has long been the most visible Muslim athlete in the United States, even more so when Islam has become a political issue.
For example, after the Sept. 11 attacks, Mr. Ali appeared on a celebrity telethon to defend his religion. He pleaded for acceptance and addressed the threat of terrorism, saying that terrorists killing in the name of Islam were wrong.
“People recognize me for being a boxer and a man of truth,” he said. “I wouldn’t be here to represent Islam if it was really like the terrorists make us look.”
Fourteen years later, Mr. Ali’s statement echoed his original comments.
“Speaking as someone who has never been accused of political correctness, I believe that our political leaders should use their position to bring understanding about the religion of Islam and clarify that these misguided murderers have perverted people’s views on what Islam really is,” he said in his statement.
In the days since Mr. Trump questioned Mr. Obama’s statement that Muslims were among America’s sporting heroes, people on the Internet responded by compiling lists of Muslim athletes. The list includes Kareem Abdul-Jabbar, a six-time N.B.A. champion who on Wednesday suggested on Time.com that Mr. Trump’s comments were more in line with Islamic State rhetoric than with a leading presidential candidate.
“Thus,” Mr. Abdul-Jabbar wrote, “Trump is ISIS’s greatest triumph: the perfect Manchurian Candidate who, instead of offering specific and realistic policies, preys on the fears of the public, doing ISIS’s job for them.”
On Thursday, a poll released by The New York Times and CBS News suggested that Mr. Trump was leading the Republican field, but that nearly two-thirds of voters were frightened by the prospect of him winning the presidency.