Muslims and Christians do not worship the same God, celebrated evangelist Franklin Graham said in response to the controversial claim by a faculty member at Wheaton College in Illinois.

In a series of tweets late Saturday night, Graham, the son of evangelist Billy Graham, laid out his opposition to the recommendation of the college’s faculty council that the school drop its plans to terminate a professor who published her belief that Islam and Christianity worship the same God, which Graham said was “no minor issue.”

Professor Hawkins of @WheatonCollege published her belief that Islam & Christianity worship the same God. This is no minor issue. 1/3 — Franklin Graham (@Franklin_Graham) January 23, 2016

I can tell you–Islam and Christianity clearly do not worship the same God. https://t.co/p6wa8YzbGJ 2/3 — Franklin Graham (@Franklin_Graham) January 23, 2016

Islam denies that God has a Son. They deny that Jesus is God. They do not believe in a Triune God– Father, Son, & Holy Spirit. 3/3 — Franklin Graham (@Franklin_Graham) January 23, 2016

How the faculty council at @WheatonCollege can support Professor Hawkins being allowed to teach students is deeply concerning. — Franklin Graham (@Franklin_Graham) January 23, 2016

In December 2015, Larycia Hawkins, who teaches political science at Wheaton College, was put on administrative leave after wearing a hijab to school in solidarity with Muslims. Wheaton is a private evangelical Christian college, which has sometimes been called the “evangelical Harvard” because of its reputation for academic rigor.

Hawkins announced that she would wear the hijab to demonstrate support for Muslims in the aftermath of the shootings in Paris and San Bernardino, California. She also used the gesture as a platform to express her belief that Christians and Muslims worship the same God.

In a separate Facebook post, Graham said both his father and mother attended Wheaton College, where they met for the first time.

“I’m surprised and disappointed that the faculty council there is now recommending the college drop their plans to terminate a professor who published that she believed Islam and Christianity worship the same God in December. This is no minor issue that should be debated,” Graham wrote.

The fundamental issue for Graham is the theological question of the nature of God and therefore the mission of the college.

“Islam denies that God has a Son,” Graham wrote. “They deny that Jesus is God. They do not believe in a Triune God–the Father, the Son, and the Holy Spirit. I can tell you–Islam and Christianity clearly do not worship the same God.”

“How the faculty council can now support this professor being allowed to teach students is deeply concerning,” he concludes.

The Wheaton College website, which identifies the school as “explicitly Christian,” includes a statement of faith that unequivocally lays out its Christian beliefs.

“WE BELIEVE in one sovereign God, eternally existing in three persons: the everlasting Father, His only begotten Son, Jesus Christ our Lord, and the Holy Spirit, the giver of life; and we believe that God created the Heavens and the earth out of nothing by His spoken word, and for His own glory,” it reads.

In her defense, Hawkins wrote: “I stand in religious solidarity with Muslims because they, like me, a Christian, are people of the book,” though it is unclear which “book” she was referring to, since the portrayal of God in the Christian Bible differs on a number of essential points from that offered in the Qur’an. Being people of a book could just as well apply to Maoists following the “little red book.”

The Catechism of the Catholic Church, for instance, states that the “Christian faith is not a ‘religion of the book.’ Christianity is the religion of the ‘Word’ of God, ‘not a written and mute word, but incarnate and living.’”

Hawkins also invoked Pope Francis as having stated “we worship the same God,” though such an affirmation is not without ambiguity. To say, as Francis did, that Muslims “worship the one living and merciful God, and call upon him in prayer,” means at minimum that Muslims do not worship an idol, or false God, but it does not imply that their understanding of God coincides with that of Christians.

While Christians, Jews, and Muslims all claim to worship “the God of Abraham,” the understanding that each has of God is not theologically identical. While all monotheists intend to worship the one God, their beliefs concerning who God is vary considerably–and sometimes in essential points, as Graham pointed out.

Thus, in 2007, Cardinal Gerhard Müller, now the prefect of the Vatican’s Congregation for the Doctrine of the Faith, could assert that Muslims and Christians “do not believe in the same God,” underscoring the differences in doctrine concerning who God is.

Christians may well continue to debate the matter of whether in their worship of God, or “Allah,” Muslims are really worshipping the God of the Bible—the God of Abraham, Isaac, and Jacob.

For now, one prominent evangelist has said “no.”

Follow Thomas D. Williams on Twitter @tdwilliamsrome