The former British prime minister Tony Blair has taught his first seminar of the "faith and globalisation" course he will lead at Yale University.
During the seminar, he said religious faith inspired some people to do harm but it also had the potential to do great things in the modern world.
In May, Mr Blair launched a faith foundation which he said would tackle poverty, challenge conflict and unite world religions.
According to the university, hundreds of students applied for places on the course.
However, Yale University president Richard Levin said Mr Blair's arrival on campus had also met with controversy.
"As is the case in Britain, a lot of young people are opposed to the Iraq war and so I think there are some students that would consider that a serious problem.
"But I also think our students are very excited about having the former prime minister of the United Kingdom here as a figure on campus," he added.
Mr Blair has also taken up lucrative jobs as an advisor to an international bank and an insurance company.
His other commitments include being the United Nations special envoy on Middle East peace and a campaigner on climate change and African poverty.