As Graham's following gained momentum, mainline institutions, such as divinity schools and Anglican churches in England and Scotland, Ivy League campuses like Harvard and Yale, among others, began to entreat him to address their constituents. Having turned down earlier invitations in 1951 and 1954 from the Protestant Council of the City of New York representing some 1,700 churches in the New York City metro area, Graham finally agreed in the spring of 1957 to organize a crusade in Madison Square Garden.

Fundamentalists, uncomfortable with Graham's affiliation with the mainline, his rejection of their exclusionary dispensationalist beliefs and his cooperation with liberals, lambasted him. They complained he had sacrificed "the cause of evangelism on the altar of temporary convenience." Graham responded to this criticism by declaring, "I would like to make myself clear. I intend to go anywhere, sponsored by anybody, to preach the Gospel of Christ if there are no strings attached to my message."

According to Wacker, after 1950 Graham declared he would not accept any invitation unless a majority of a city's Protestant ministers gave at least tacit support. Journalists' accounts of his crusades recurrently reported the prevalence of attendees from mainline churches and the high level of cooperation from mainline pastors.

Graham's engagement in New York opened on May 15, 1957 to a gathering of 18,000. Originally slated to conclude after six weeks, as a result of its unprecedented success, it kept being extended for a total of four months. When all was said and done, a total of more than two million individuals heard Graham speak in-person, of which 61,000 made personal faith commitments, with at least 10,000 new members added to mainline church registers.

In Great Souls: Six Who Changed the Century, David Aikman reflects that Graham, more so than any other Protestant leader in ages past, has "successfully articulated the central features of the Christian doctrine...and at the same moment mobilized global Protestant Christianity in pursuit of them." Graham was able to do so by emphasizing that Christians' disagreements over particular doctrines were inferior to the beliefs and burdens they held in common, particularly to impact the culture and communities with the Gospel.

Ross Douthat writes in Bad Religion that Graham "almost singlehandedly revitalized" the tradition of revivals in America; his crusades encouraged evangelicals to relinquish the more exclusionary tenets of fundamentalism and to foster cooperative relationships with the mainline. No evangelist leader since Graham has, in Douthat's eloquent phrasing, managed to achieve a "delicate balance between evangelical rigor and openhanded ecumenism, between a Christian particularism and a universal Americanism, between warnings of God's justice and promises of God's all-encompassing love."

Grant Wacker concludes, "In the end, assessing Graham's legacy for his own evangelical subculture may be less important than assessing his legacy for the mainline...That said, the hardest challenge might be to remember that the man and the mountain were not the same."