Belief in Jesus and living a Christian life are both essential for salvation. The “once saved, always saved” or unconditional eternal security was not a doctrine that was taught by the ancient church, nor for that manner, by any well-known theologian before John Calvin. This doctrine is, in fact, completely foreign in the history of Christianity.
The American Revivalism Movement in the late 1800s and 1900s brought the first wave of American fundamentalists into being, with their central “eternal security,” “once-saved-always-saved,” “born again” doctrine.
Since the First Century, the Catholic Church has taught that baptism was performed for the forgiveness of sins and to receive the gift of the Holy Spirit (see Acts 2:38). That is the “water” and “spirit” that is referred to in Jesus’ discourse to Nicodemus in John 3:4.
First Peter 3:20 also says that we are saved by baptism.
Take a look at the Old Testament:
In Ezekiel 36:25-27, it says, “I will sprinkle clean water upon you, and you shall be clean from all your uncleannesses…a new heart I will give you and a new spirit I will put within you…and I will put My spirit within you…” Here, in the Old Testament, we have a foreshadowing of New Testament baptism.
Now, let’s see if the New Testament corresponds to what we just read in Ezekiel. Acts 2:38, “Repent, and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins; and you shall receive the gift of the Holy Spirit.“
I was a fundamentalist nondenominational Christian for over two decades. I believed in eternal security, with no reservation. But after converting to Catholicism and studying the Church fathers and early Christians in the light of scripture, I believe that the eternal security doctrine of the Reformation is in error. Just like the Arian Heresy, Gnosticism and Donatism, and all the other man-made doctrines that have permeated Christian teaching at times through the centuries, the “eternal security” teaching will eventually take its place with the other heretical teachings.
The sad truth is that many people will see Hell because of it.