The altar call was born out of pragmatism.
Pragmatism: A movement consisting of varying but associated theories, originally developed by Charles S. Peirce and William James and distinguished by the doctrine that the meaning of an idea or a proposition lies in its observable practical consequences. (from dictionary.com)
In other words the cause is defined by the effect. Pragmatic thinking basically says the meaning of a cause can be defined by its effect. Now for the altar call. Pragmatic reasoning would say the fact that during an altar call people move forward and make a decision to follow Christ, means that the altar call itself is a means of converting people to Christ. The altar call is defined by the decisions made at the altar.
So what is wrong with all of this? We would say that people making decisions for Christ is a good thing right?
You certainly do not hear of altar calls, or anything remotely similar in scripture. Yet the altar call has become the hallmark of many evangelical churches. Many churches will view a high number of people at an altar call as evidence of sucessful preaching and a low number as evidence of poor preaching. (Notice the pragmatic reasoning.) The pressure of getting a large number of people to the altar as driven preachers to change their message. Preachers will preach in a way that manipulates the congregation using psycology and brings them to a point where they are emotionally wrapped into their message and their guard is down at that point they bring in the gospel and the gospel makes sense and the people stream down the aisles to the altar to make a decision. The issue is that for many if not most of these people the altar call was an emotional experience that was not spirtual rebirth. What complicates this even more is when the preacher assures them of their eternal security based on the prayer they made at the altar. This whole altar call salvation is based on an unbeliever making a decision, and praying a prayer and is often done in an emotionally altered state. It is the works of a man, coming forward and praying the prayer that brings them supposed salvation.
True salvation comes from being born again from above.
(I have to stop right now, this post will be continued check back in for the conclusion shortly.)