I read this online ebook about two or so years ago, Tamara Hartzell does a very good job of warning about the "new global spirituality" and false teachings being promoted by Rick Warren and other teachers joined with him.
Sadly, this departure from the faith will be so great that the Lord Jesus Christ asks us to consider whether He will actually find faith on the earth when He returns (see Luke 18:8). Since Christians today are trading in the truth of the faith for interfaith unity and are falling for the false gospel of the (New Age) New Spirituality that says all religions are equally valid paths to God, it's no wonder the Lord Jesus Christ asked this.
The universal religion with its spiritual transformation is not coming; it is here. The Angel of light's kingdom is gathering together "all men of peace" from "every world religion" "as the embodiment of the emerging Kingdom of God on earth."* In this emerging interfaith kingdom there is:
"One Truth," yet many theologies;
"One God," yet many paths;
"One Church," yet many expressions; and
"One Divine Life," yet many 'little Christs.'
Despite its deceived claims that its message hasn't changed, today's Christianity is embracing the teachings of the counterfeit kingdom
It is very worthwhile reading, and for me helped to put the pieces of the puzzle together in terms of the evangelical world signing on to the one world religion.