The Manhattan Declaration does call "Christians" to unite in "the Gospel," "the Gospel of costly grace," and "the Gospel of our Lord and Savior Jesus Christ in its fullness."  Furthermore, Jews, Muslims, Mormons and other non-Christians are not invited to sign the document even though they generally hold to the same positions about abortion, marriage, and freedom of religion. One interesting validation of the grounds for this controversy came from the following Google search: "Franklin Graham Manhattan Declaration."  Among the hits returned was a gay activist website commenting on Graham's absence as a signatory. The author, Timothy Kincaid, who professes to be a Christian and takes offense at the Manhattan Declaration's bias against gay Episcopal bishops, commented: "…this manifesto has less to do with social goals and more to do with Christian definition." Such an observation by Kincaid, who is clearly opposite Sproul theologically, politically, and socially does, in fact, corroborate Sproul's and others' reading of the Manhattan Declaration as an attempt to define who is and who is not "Christian."

Other Evangelical leaders declining to support the Manhattan Declaration also cite the errant ecumenical tone of the document. R.C. Sproul is joined in his view by notable leaders like John Piper and John MacArthur who sees the Manhattan Declaration as an implicitly theological statement… a flanking maneuver that attempts to redefine Christianity without addressing long-standing issues that have been around since the 1500s—the time of the Protestant Reformation.

Such assertions appear to be grounded in fact since in his commentary on November 25, Chuck Colson—one of the three authors of the Manhattan Declaration—said that the Manhattan Declaration is "a form of catechism for the foundational truths of the faith."

Other Evangelical leaders like Mark Driscoll, Alistair Begg and Michael Horton believe that the Manhattan Document reduces Christianity to mere Trinitarianism and degrades the heart of Christianity, namely, the Gospel of Jesus Christ to a set of ethical standards and a non-descript gospel.