Here is the document

Christians, when they have lived up to the highest ideals of their faith, have defended the weak and vulnerable and worked tirelessly to protect and strengthen vital institutions of civil society, beginning with the family.

We are Orthodox, Catholic, and evangelical Christians who have united at this hour to reaffirm fundamental truths about justice and the common good, and to call upon our fellow citizens, believers and non-believers alike, to join us in defending them. These truths are:

1. the sanctity of human life
2. the dignity of marriage as the conjugal union of husband and wife
3. the rights of conscience and religious liberty.

Inasmuch as these truths are foundational to human dignity and the well-being of society, they are inviolable and non-negotiable. Because they are increasingly under assault from powerful forces in our culture, we are compelled today to speak out forcefully in their defense, and to commit ourselves to honoring them fully no matter what pressures are brought upon us and our institutions to abandon or compromise them. We make this commitment not as partisans of any political group but as followers of Jesus Christ, the crucified and risen Lord, who is the Way, the Truth, and the Life.

http://manhattandeclaration.org/

At first glance, the three stated truths are good, but what is missing here?

Here is what John MacArthur says:

By John MacArthur

Here are the main reasons I am not signing the Manhattan Declaration, even though a few men whom I love and respect have already affixed their names to it:

• Although I obviously agree with the document’s opposition to same-sex marriage, abortion, and other key moral problems threatening our culture, the document falls far short of identifying the one true and ultimate remedy for all of humanity’s moral ills: the gospel. The gospel is barely mentioned in the Declaration. At one point the statement rightly acknowledges, “It is our duty to proclaim the Gospel of our Lord and Savior Jesus Christ in its fullness, both in season and out of season”—and then adds an encouraging wish: “May God help us not to fail in that duty.”  Yet the gospel itself is nowhere presented (much less explained) in the document or any of the accompanying literature. Indeed, that would be a practical impossibility because of the contradictory views held by the broad range of signatories regarding what the gospel teaches and what it means to be a Christian.

• This is precisely where the document fails most egregiously.  It assumes from the start that all signatories are fellow Christians whose only differences have to do with the fact that they represent distinct “communities.” Points of disagreement are tacitly acknowledged but are described as “historic lines of ecclesial differences” rather than fundamental conflicts of doctrine and conviction with regard to the gospel and the question of which teachings are essential to authentic Christianity.

• Instead of acknowledging the true depth of our differences, the implicit assumption (from the start of the document until its final paragraph) is that Roman Catholics, Eastern Orthodox, Protestant Evangelicals and others all share a common faith in and a common commitment to the gospel’s essential claims. The document repeatedly employs expressions like “we [and] our fellow believers”; “As Christians, we . . .”; and “we claim the heritage of . . . Christians.” That seriously muddles the lines of demarcation between authentic biblical Christianity and various apostate traditions.

• The Declaration therefore constitutes a formal avowal of brotherhood between Evangelical signatories and purveyors of different gospels. That is the stated intention of some of the key signatories, and it’s hard to see how secular readers could possibly view it in any other light. Thus for the sake of issuing a manifesto decrying certain moral and political issues, the Declaration obscures both the importance of the gospel and the very substance of the gospel message.

• This is neither a novel approach nor a strategic stand for evangelicals to take.  It ought to be clear to all that the agenda behind the recent flurry of proclamations and moral pronouncements we’ve seen promoting ecumenical co-belligerence is the viewpoint Charles Colson has been championing for more than two decades. (It is not without significance that his name is nearly always at the head of the list of drafters when these statements are issued.) He explained his agenda in his 1994 book The Body, in which he argued that the only truly essential doctrines of authentic Christian truth are those spelled out in the Apostles’ and Nicene creeds. I responded to that argument at length in Reckless Faith. I stand by what I wrote then.

In short, support for The Manhattan Declaration would not only contradict the stance I have taken since long before the original “Evangelicals and Catholics Together” document was issued; it would also tacitly relegate the very essence of gospel truth to the level of a secondary issue.  That is the wrong way—perhaps the very worst way—for evangelicals to address the moral and political crises of our time. Anything that silences, sidelines, or relegates the gospel to secondary status is antithetical to the principles we affirm when we call ourselves evangelicals.

John MacArthur