Saved by a Prayer

The Myth
When people become Christians, it usually starts with a prayer, known as "The Sinner's Prayer". The prayer essentially summarizes our need for forgiveness, our thankfulness to Jesus for paying for our sins when He died on the cross, and our new commitment to follow Him. Here's an example:

"God, I know that I have sinned against you and that my sins separate me from you. I am truly sorry. I now want to turn away from my sinful past and turn to you for forgiveness. Please forgive me, and help me avoid sinning again. Thank you for dying on the cross to pay for my sins. Please reign in my heart and make me your disciple from this day forward. My greatest purpose in life is to follow your example and do Your will for the rest of my life. In Jesus' name I pray, Amen."

Many Christians treat this as an incantation, and believe that anyone who has said this prayer at any time is immediately "saved."

The Reality
I think (or hope) most Christians will claim to recognize that this prayer has no magical ability to send people to Heaven or make their life perfect, and in itself has no actual bearing on the rest of someone's life. We all know it's just a verbal expression of an inward transformation, right?
Unfortunately, a common problem we have is acknowledging things verbally, but not necessarily thinking it through. People do this when they act like the "The Sinner's Prayer" has so much meaning when spoken, but then don't concern themselves with making sure that the verbal commitment is fulfilled with a change in their lifestyle.
Following Christ is not just some one-time commitment that saves you: You don't just say the prayer, and then that's your ticket to Heaven. The word Christian means like Christ. In other words, being a Christian means a daily commitment to trying to be like Jesus; and that's a point I don't feel is made clear in many altar calls.
We're quick to emphasize the Romans 10:9 part of becoming a Christian, which talks about believing and confessing, but then act like no further action should be taken on our part. We've got the insurance plan and are good to go, and ignore the words of John and James that say our faith must result in righteousness.

Why It Matters
When we treat our covenant with God like it's a mystical password that gets us into heaven, then we are essentially rendering it meaningless. As anyone who has ever heard of a politician or made a New Year's resolution can tell you, the words you say hold only as much meaning as the commitment behind them.
If you promise your son that you'll take him to a movie this weekend, and Monday comes around and you failed to fulfill your promise, then it doesn't matter how sincere that promise felt: if you didn't keep the promise, it holds no value. Why should our commitment to God be viewed any differently?

As a side note...
The whole "repeat after me" thing has bothered me for a long time. I'm concerned that it puts too much emphasis on the words themselves, and not the heart behind them. Rather than repeating a prayer verbatim, I'd prefer to see the evangelist provide an outline of what God requires of us, and then exhort the new believers to pray to God in their own words, from their own hearts. But this is simply a matter of opinion, and in no way is meant to say that repeating after someone is an invalid form of prayer.