Wheaton College, the prestigious evangelical establishment which includes Billy Graham among its alumni, is facing a public backlash because of a decision that appears to align it with theological ultra-conservatives.

One of its teachers, Prof Larycia Hawkins, said she was going to wear a headscarf during Advent as a sign of "religious solidarity with Muslims", because "they, like me, a Christian, are people of the book". She added: "And as Pope Francis stated last week, we worship the same God."

Her action came after rising pressure on Muslims including from Republican presidential hopeful Donald Trump, who said he would ban them from entering the US.

Hawkins was suspended from her post, with Wheaton citing theological concerns though she has reaffirmed her commitment to the 12 statements comprising Wheaton's articles of faith.

"While Islam and Christianity are both monotheistic, we believe there are fundamental differences between the two faiths, including what they teach about God's revelation to humanity, the nature of God, the path to salvation and the life of prayer," the college said.

Now, however, students and clergy have fought back. There were protests on the campus yesterday from students calling for her reinstatement and an apology from the college. More than 20 Christian clergy also appeared with Hawkins at a news conference to show their support.

A letter delivered by the students to Wheaton's President Philip Ryken and Provost Stan Jones said: "We believe there is nothing in Dr Hawkins' public statements that goes against the belief in the power and nature of God, Christ, or the Holy Spirit that the Statement of Faith deems as a necessary requirement for affiliation with Wheaton College."

Ryken told protesters he appreciated the "peaceful spirit" of their demonstrations.

According to the Chicago Tribune, Rykens told the group: "I really want to affirm your right to disagree with a decision by the administration. "I also want to affirm the things you see in Dr Hawkins, the values. Those are things I've seen firsthand as well.

"At some level, I understand the frustration, and also the pain."

Hawkins' statement has faced criticism from conservative theologians outside the college. Denny Burk, a professor of biblical studies at the Southern Baptist Theological Seminary, said Hawkins had implicitly denied Christian teachings.

"We're people of the book, but our books are very different," he said. "They're witnessing to two different ways of salvation. The Bible is witnessing to Jesus Christ, the son of God. That's unique of all the world religions, and that uniqueness was what I thought was missing from what she said."

However, Wheaton's own conduct has also been widely criticised, with Yale theologian Miroslav Volf – who has lectured at Wheaton on the question of whether Christians and Muslims do worship the same God – saying: "She has not denied any of the Christian claims that God was the Holy Trinity, that God was incarnate in Jesus Christ and Christ is the saviour of the world who died on the cross."

Wheaton is sometimes known as the "Harvard of evangelicalism". The apparent lack of theological awareness in its treatment of Hawkins seems unlikely to reflect well on its academic standing.