Fr. Emmanuel Charles McCarthy, a Melkite priest has this to say:-
The Manhattan Declaration is a PR trick. It is condemning in a public forum what Jesus certainly would have rejected while approving—via public and private silence and active support in daily operation for decades—what Jesus equally and unequivocally rejects. All the signatories, I know, are old hands at doing this nationally and locally: taking the moral high ground on denouncing what is inconsistent with the Way of Jesus on some issues, while saying nothing on or overtly endorsing other matters that are equally contrary to the Will and Way of God as revealed by Jesus. Natural human reason is their universal loophole to justify overriding the self-evident teachings of Jesus on Nonviolent Love of friends and enemies and thereby follow Him by killing and maiming millions in war. But, remember, Jesus is the Logos (Word) of God, the Source and ultimate norm of what they call natural human reason (which is itself, in our view, the gift of a beneficent God), and in the very nature of the human person. A Jesus, that is Logos, de-nuded understanding of natural human reason [See my "Christian Just War Theory: Spiritual Quicksand" essay in my book Christian Natural Law Just War Theory:The Logic of Deceit ] is how they all attempt to by-pass those logical network of implications and applications of the teaching of Jesus that they find inconsistent with their interests to be faithful and obedient to. God is not illogical, says Pope Benedict XVI in his Regensburg University address. His exact words are Not to act reasonably (with logos) is contrary to the nature of God...(T)he truly divine God is the God who has revealed himself as logos and, as logos, has acted and continues to act lovingly on our behalf...Consequently, Christian worship is "logic latreía" -- worship in harmony with the eternal Word and with our reason...Not to act "with logos" is contrary to God's nature.
However, Jesus is the Logos, who is the incarnation of God, God, and who is the source and creator of natural law and therefore cannot communicate one truth as God's Will and Way in the Sermon on the Mount and the Sermon on Golgotha and the logical opposite of that truth as also truth via natural law, i.e, via the proper use of natural human reason in the very nature of the human person—that the Logos created. Natural human reason itself logically tells us with transparent clarity that if a use of Logos-given and Logos-imbued natural human reason arrives at a moral conclusion logically contrary to what the Logos incarnate, Jesus, taught, when He dwelt among us, a manlike us in all things but sin, then it is self-evident we have to be employing our Logos-given and Logos-imbued understanding of the Logos-created natural law incorrectly.
The Manhattan Declaration is but latest strategy in the ancient game of moral charades which Constantinian Christians and Churches—that have bonded with the economic and political powers of one of the kingdoms of this world—have played for 1700 years. The Manhattan Declaration is an arch-misrepresentation of what Jesus taught and meant by "Follow me." It intentionally mis-directs people away from other equally serious and grave logical applications of the teachings of Jesus on the sanctity of life and the Will and Way of God, e.g. war. Therefore, it is an exercise in deceit—and hence a contemporary instrument and blatant example of intentional half-truth-false-witness.