Question: "What is the emerging / emergent church movement?"
Answer: The emerging, or emergent, church movement takes its name from the idea that as culture changes, a new church should emerge in response. In this case, it is a response by various church leaders to the current era of post-modernism. Although post-modernism began in the 1950s, the church didn't really seek to conform to its tenets until the 1990s. Post-modernism can be thought of as a dissolution of "cold, hard fact" in favor of "warm, fuzzy subjectivity." The emerging / emergent church movement can be thought of the same way.
The emerging / emergent church movement falls into line with basic post-modernist thinking—it is about experience over reason, subjectivity over objectivity, spirituality over religion, images over words, outward over inward, feelings over truth. These are reactions to modernism and are thought to be necessary in order to actively engage contemporary culture. This movement is still fairly new, though, so there is not yet a standard method of "doing" church amongst the groups choosing to take a post-modern mindset. In fact, the emerging church rejects any standard methodology for doing anything. Therefore, there is a huge range of how far groups take a post-modernist approach to Christianity. Some groups go only a little way in order to impact their community for Christ, and remain biblically sound. Most groups, however, embrace post-modernist thinking, which eventually leads to a very liberal, loose translation of the Bible. This, in turn, lends to liberal doctrine and theology.
For example, because experience is valued more highly than reason, truth becomes relative. Relativism opens up all kinds of problems, as it destroys the standard that the Bible contains absolute truth, negating the belief that biblical truth can be absolute. If the Bible is not our source for absolute truth, and personal experience is allowed to define and interpret what truth actually is, a saving faith in Jesus Christ is rendered meaningless.
Another area where the emerging / emergent church movement has become anti-biblical is its focus on ecumenism. Unity among people coming from different religious backgrounds and diversity in the expression of corporate worship are strong focuses of the emergent church movement. Being ecumenical means that compromise is taking place, and this results in a watering down of Scripture in favor of not offending an apostate. This is in direct opposition to passages such as Revelation 2:14-17, Jesus' letter to the church of Pergamum, in which the Church is warned against tolerating those who teach false doctrine.
False doctrine seems to abound within the emerging / emergent church movement, though, as stated previously, not within every group espousing emerging / emergent church beliefs. Because of this, care must be taken when deciding whether or not to become involved with an emergent church group. We all need to take heed of Matthew 7:15-20, "Watch out for false prophets. They come to you in sheep's clothing, but inwardly they are ferocious wolves. By their fruit you will recognize them. Do people pick grapes from thorn bushes, or figs from thistles? Likewise every good tree bears good fruit, but a bad tree bears bad fruit. A good tree cannot bear bad fruit, and a bad tree cannot bear good fruit. Every tree that does not bear good fruit is cut down and thrown into the fire. Thus, by their fruit you will recognize them."
While seeking new ways to witness to a changing culture is admirable, utilizing ways which compromise the Truth of the Gospel in any way is nothing more than promoting false doctrine and leading others away from Christ instead of to Him.