Some of the Christian churches of this world have a doctrine titled "Eternal Security," and some, a few maybe, "Extreme Eternal Security." This essentially postulates that once one has accepted Jesus Christ's blood, salvation is assured. This doctrine almost makes Christian life seem as though it is a walk in the park.
This doctrine was one of the central themes of the Protestant Reformation, as theologians like Martin Luther and John Calvin moved to reject doctrines that they considered "Catholic." The central theme of this doctrine claims that the called individual has absolutely no part in the salvation process. That is the one they call "Extreme Eternal Security."
Belief in this teaching was one of the major reasons why Martin Luther rejected the book of James. He called it "an epistle of straw," seeing it clearly rejected eternal security. James makes it clear that a person's works are important to his salvation, because he states that "faith without works is dead." Dead faith will not lead to a resurrection to life.
We can learn from this that rejection of clearly-stated biblical truth is not limited to the man in the street. People considered great, like Martin Luther and John Calvin, got things wrong too. Even though it may have been pointed out to them by others, they rejected it in favor of what they had devised.
Did not Jesus—Christianity's Founder—say very clearly that the way to life is difficult and narrow? Why are there so many warnings and admonitions not to turn out of the way if a successful conclusion is virtually assured as soon as one begins?
John W. Ritenbaugh
Does Doctrine Really Matter? (Part Four)
Many will seek to enter the Kingdom of God but be barred from it because of flagrant sin. Jesus will refuse to answer the knock of unruly sinners who have rejected salvation, though they weep and grind their teeth when they find out they cannot enter God's Kingdom. When the third resurrection arrives, all humanity will have had the opportunity to be saved; everyone's ultimate destiny will have been eternally set. It will be too late for anyone who, after coming to the knowledge of the truth, sins willfully and thereby rejects eternal life. Those who reject God and His way of life must then reap the consequences of that decision - the second death following the third resurrection to judgment.
Martin G. Collins
Basic Doctrines: The Third Resurrection