Kevin DeYoung has a thorough and balanced explanation of the controversy, including why there is a controversy and the positions of both sides.
here is his position:
So where do I stand on The Manhattan Declaration? Well, I wish I would have listened to my initial hesitation about signing these sorts of documents. The Declaration does not need my signature to make it significant and I don’t need people to misunderstand what my support means. But having signed it (only as one of the crowd), I still agree with the Declaration and feel no pang of conscience for supporting it. If it comes out that the Declaration was meant to minimize the deepest divisions between Evangelicals and Catholics, then I will regret my support. But as it stands, I agree with Mohler’s reasons for signing the document and share his understanding of what signing does and does not mean
Go read the rest of Kevin’s thoughtful post.