There is an idea that a person can pray a prayer once with the proper amount of sincerity and be eternally guaranteed of salvation. It is perhaps one of the more interesting phenomena that I have witnessed in American Christianity (and has been exported abroad through missions). I remember when I was in junior high thinking that this practice smelled wrong. As I have reflected further upon it, I think that the idea of “eternal security” (that once you are “saved” you are always “saved”) and its application to the sinner’s prayer has become a form of magic. But, not just any magic. It is Jesus Magic.
The sinner’s prayer is one of the most common expressions of Jesus Magic in our culture. I call this Jesus Magic because the idea that I can say words that somehow require God to maintain my salvation through the uttering of a short prayer at one moment is magical. I am using magic here to refer to the idea that we alter and shape reality through supernatural power that is invoked through spoken words. Indeed, the “sinners prayer” is at times treated as a supernatural invocation, the uttering of which binds God to provide a certain flavor of the eternal state apart from that person doing much or anything else. Imagine the ability to control how God will judge you at the final judgement through praying a prayer at one point in your life. It is rather preposterous and runs counter to the things that Jesus and the Apostles actually wrote about the final judgement.
This form of belief is practically evident after things like mission trips, vacation Bible school, or other such “outreach” events. After things like this, the metrics used to measure the success is often based upon how many people “got saved/ accepted Jesus” through praying the sinner’s prayer. Biblically speaking, this is an aberration from the teaching of Jesus. Jesus had a lot to say about what was required to follow Him. None of the things that Jesus said about following Him or how to be saved ever involved saying a prayer. Jesus had a lot to say about following Him involving self-denial (take up your cross and follow me) and doing things (such as feeding the hungry, clothing the naked, taking care of the poor, etc...). It is a very interesting exercise to look through the Gospels and see what Jesus set forth as the requirements to follow Him. I actually did an exercise like this during my time in Bible College and the study from writing that paper was the final scoop of dirt that buried the once saved always saved view for me. When I read the Gospels, I am rather intimidated by what Jesus has to say about what is required for those who will follow Him (self-denial and death Matthew 16:24, sell all your possession Luke 18:12, forsaking your employment Matthew 4:19 and 9:9, etc…).
There are theological systems which prevent this tragedy. Classically speaking, the liturgical practices of the early church preclude this notion of salvation. This continues among both the Roman Catholics and the Orthodox. More recently speaking, both Calvinism and Arminianism, through different approaches, preclude the idea that anything a person could choose once would require God to offer eternal salvation. Calvinists (classically speaking) would affirm that God chooses whom He will save and those people will persevere in the faith. Arminians (again, classically speaking) would hold those who continue to choose to follow God will be saved. Through an interesting blending of these two systems divorced from both Scripture and tradition, this form of Jesus magic has emerged. It is both dangerous and deleterious to your mind and soul.
 I am aware that some would posit that transubstantiation is also a form of magic. I do not think that this is a fair comparison for several reasons. According to the actual liturgical practice, the Holy Spirit is the one who does the work just as happened in the incarnation of Jesus and we would not posit that the angel Gabriel was the one who brought about the incarnation in his announcement.