"What's missing from this document is a clear statement about what Christianity really is and how we can come together to talk with Muslims from our unique, distinctive, biblical standpoint," Piper said in a public statement last month.
He rejected the letter's emphasis on the common ground of the love of God, arguing that the love of God for Christians is starkly different from that of Islam.
"The love of God is ... uniquely expressed through Jesus Christ as the propitiation for our sins because he died on the cross and rose again. All those things, Islam radically rejects," Piper stressed. "So they do not believe in the love of God we believe in."
The Rev Canon Dr Patrick Sookhdeo, director of the Institute for the Study of Islam and Christianity and founder of the Barnabas Fund, applauded the effort of the Muslim leaders in reaching out to Christian leaders but called the Christian response a "betrayal" and "sell-out" of the Christian faith.
Following such criticism, Wheaton's Litfin realised he had "moved too quickly" to sign the statement in his eagerness to support its strengths, including peace-making.
Recognising that the statement could have been written differently to avoid vagueness of the Christian faith, Litfin said he could not support a statement that speaks as if the Muslim Allah and the God that Christians believe in are the same.
"I needed to back away," he said regarding his retraction.
At the same time, he said he does not criticise others "who do not share these qualms".
Noting that he was not pressured to withdraw his name from the statement, Litfin said, "It was simply a matter of conscience, combined with the fact that I had put the College on the line in a way I was no longer comfortable in defending."
Other signatories of the Christian response showed no qualms over their endorsement.
"I still agree [with the statement]. I don't have reservations," said Roy Oksnevad, director of Muslim Ministries at Wheaton College's Billy Graham Center, according to The Record.
