“Once saved, always saved” has become an evangelical cliché which grossly misrepresents the doctrine of the perseverance of the saints. It has unfortunately been used by immature Christians and perhaps even unsaved “Christians” as a license to sin.

Here’s what John Piper has to say about the subject in his book Future Grace (via Delight in Truth friend Gabe Bogdan):

“A few years ago I spoke to a high school student body on how to fight lust. One of my points was called, “Ponder the eternal danger of lust.” I quoted the words of Jesus–that it’s better to go to heaven with one eye than to hell with two–and said to the students that their eternal destiny was at stake in what they did with their eyes and with the thoughts of their imagination…

After my message… one of the students… asked, “Are you saying then that a person can lose his salvation?”

…This is exactly the same response I got a few years ago when I confronted a man about the adultery he was living in…

I pled with him to return to his wife. Then I said, “You know, Jesus says that if you don’t fight this sin with the kind of seriousness that is willing to gouge out your own eye, you will go to hell”…

As a professing Christian he looked at me in utter disbelief, as though he had never heard anything like this in his life, and said, “You mean you think a person can lose his salvation?”

…So I have learned again and again from firsthand experience that there are many professing Christians who have a view of salvation that disconnects it from real life, and that nullifies the threats of the Bible, and puts the sinning person who claims to be a Christian beyond the reach of biblical warnings.

I believe this view of the Christian life is comforting thousands who are on the broad way that leads to destruction (Matthew 7:13)…

The main concern of this book is to show that the battle against sin is a battle against unbelief. Or: the fight for purity is a fight for faith in future grace.

The great error that I am trying to explode is the error that says, “Faith in God is one thing and the fight for holiness is another thing… The battle for obedience is optional because only faith is necessary for final salvation.” (John Piper, Future Grace pg. 330-331 and 333)

It is a grave error to separate obedience to the Word from an initial conversion type event. Disobedience, lack of striving for holiness, and lack of perseverance in the faith may be indicative that the professing Christian is not saved.