In this post, I linked to an article which addressed this question. And it's a great article.
But I've been wanting to add a second part to this. A warning to those who profess Christ but may not really be his.
I remember reading a book some time ago that told a story of a man who videotaped a skydive event. He was part of it. He watched the others dive from the plane, and then he followed -- his camera running. They all fell earthward and as they did, the other skydivers held hands, made formations and did stunts. Then they began opening their parachutes. The camera kept rolling.
One by one, the parachutes opened. What a beautiful sight! But then something apparently went very wrong. Suddenly, the camera began swinging wildly. It became obvious that there was great panic by the way the camera kept moving. Then nothing.
What happened? The found that the person with the camera had failed to put on a parachute! He thought he was just as safe and secure as the other skydivers. He enjoyed the fall and watched the show. He really believed he had nothing to worry about. But he found out, too late, that he was falsly assured about his safety.
Jesus says in Matthew 7 that there will come a day of great catastrophe for many who profess Christ. They will expect to enter heaven, only to hear "...depart from me, I never knew you...", and that will be an eternal catastrophy. Even while those words are shocking them, they will sink into an eternal hell from which they will never emerge. Their "spiritual experiences" will prove to be false evidence of a salvation they never had. They really thought (or should I say 'think' because some of you reading this may be among that number!) they were converted because "God Stuff" happened to them, only to find out experiences prove nothing.
See, conversion is not found in a profession of faith. Conversion is not found in walking an isle, signing a card, or praying a prayer. It isn't even found in martyrdom. It is not, according to John 1, by human decision but by a sovereign act of God.
Salvation is, as Paul said, by grace through faith and even faith is a gift of God (we know that because the Greek word for "that" is feminine as is the word for "faith").
So, what is my point? Simple. Look for fruit. Look for the fruit of obedience. Look in Romans chapters 1 and 16. Both chapters tell of "the obedience of faith". In other words, "the obedience that comes from faith". Don't agree with me? Read Hebrews 11. Here you see the repeated working out of faith in demonstrated obedience. James would say they were showing their faith "by their works". And they did.
Read John's first epistle. The entire epistle was written to help John's readers tell those who profess Christ from those who really possess Christ. The "if we sayers" are the unsaved and the "if we doers" are the saved.
True Christians continue to love the bretheren. Do you love those who preach the pure unadulterated Gospel? Or do you merely tolerate them or maybe even become angered by them because they are "offensive" or "narrow". Be careful; you may not be shunning mere people. You may be refusing the real Gospel.
Do you continue to find excuses for sin patterns in your life? Then you have little or no right to assurance of salvation. Why? because John tells us that, on the negative side, a true convert will not practice sin. John adds that a true Christian cannot "continue to practice sin because His seed abides in him...". As he later says, a true Christian will "continue to purify himself". That is the positive side.
Today, we hear a popularized "gospel". It really has nothing to do with the true Gospel. It basically says "Hey, wanna be happy and fulfilled? Pray this prayer and you're in!" That isn't the biblical Gospel, but a false Gospel that is known by a very wide gate. Jesus said the gate is narrow, as is the way. The contemporary gospel knows nothing of repentance. After all, that would alienate "seekers".
Well, I have news for you. If anyone is really seeking Christ, you need to tell them how to get to Christ. And Jesus said it's by denying yourself, taking up your cross (death to self) and following (obeying and conforming to) Him. Nothing more. Nothing less. And it begins with repentance.
If you leave this out, you have a false gospel. And you really need to, as Paul said in 2 Corinthians, "examine yourself to see if you are in the faith."
There is only one thing that matters. That is "What does the Bible say about salvation".
We live in days of great apostasy. Many are those in prominence who are gathering many around them. They have charismatic personalities. They say great things. And they appear to be so noble. They promise happiness in this life. They promise to solve the world's problems. The problem is that God never promised these things. Not in this life.
One promise that Jesus made was that "...those who seek to live godly in this present evil age shall suffer persecution." So, I ask you, when was the last time you took a pounding for a legitimate expression of your faith? And yes, I have to ask myself that as well.
So, I ask you to take a serious look at your life. Do you really know Him? I remember a song from years ago; "Hey You, I'm into Jesus". I hate that song. I don't care if you are into Jesus any more than I care if you are "into" stamp collecting. What I want to be sure of is "Is Jesus Into Me?" It isn't "do I know Jesus". It's "Will Jesus say He Knows Me?"
Let us ask that question daily.