1Jn 2:17 And the world passeth away, and the lust thereof: but he that doeth the will of God abideth for ever.
1Jn 2:18 Little children, it is the last time: and as ye have heard that antichrist shall come, even now are there many antichrists; whereby we know that it is the last time.
1Jn 2:19 They went out from us, but they were not of us; for if they had been of us, they would no doubt have continued with us: but they went out, that they might be made manifest that they were not all of us.
I've had this conversation several times with persons who truly believe they were once saved and eventually have fallen from that "saving faith" into all sorts of error (atheism, agnosticism, Buddhism, Judaism, anything but the truth of God's word, just holding to the fragments that appeal to them) or persons who have "friends" who were "once saved" and now are not.
I can honestly say that if you do not believe God now, you never did. How can I say that? I didn't know these people, and I don't really know them now, so how can I make such an assessment? By God's word, the Bible. The Bible says so. Is that so shocking? Is that a ridiculous reason to accept that as a fact? Then the Christians who say they believe these false ones over the Bible are also suspect for possibly being the same type of (non)Christians.
These are interesting times, and MANY are falling out with the Church. Some may eventually turn to Christ in truth, but I sadly believe that many will not. These had an "appearance of Godliness" but they rejected His power (the Bible tells us 2 Timothy 3:5) and they are "ever learning" but never actually coming to the full truth (2 Timothy 3:7). They put more faith into their own faulty belief system than understanding the fact that none of us can fully comprehend something (and Someone) that is completely out of our league, but by His power and strength is able to grow us to learn truly about Him, and grow us to be His brothers and sisters by maturing in His grace and His knowledge, which is far superior to anything we can come up with on our own. The fact that they don't want to give up on their own ability to come up with these things causes them to judge God as "unfair" and "unloving". Unfair? Yes. Because we all deserve hell, so the fact that those who truly grow in Him won't go to hell is very unfair. It's called grace because we do not deserve it. I don't want fair because of the fact that it would be completely fair to send me to hell.
I think I'm only observing the beginning of this trend, this falling away. I believe many will fall out, that there are many "pew warmers" who think they believe God, and do not. They go for the good times, to be proper American citizens, or at least go to see their friends, etc, but as far as having a relationship with Jesus? Truly? He will say to many: "I never knew you" (Matthew 7:23)
In the above (2 John 2:19) we find that it is actually a good thing that the falling away occurs, because the appearance of godliness is outed for what it really is. It isn't godliness at all, only something that has that appearance, on the surface. If it were true it would be throughout those individuals lives, permeating their very existence, and to the point they would never abandon the Lord who so mercifully and lovingly saved them from their wretched selfish lives. It just wouldn't happen, so the wheat is then being separated from the tares. The tares look similar to wheat, but when both mature, the tares reveal what they really are. Their fruit has a black fungus on it that is poisonous if ingested, causing sleepiness in small amounts, or if concentrated into a juice/oil solution it can even cause death. What appropriate symmetry and symbolism. The message such persons "preach" is that there is the possibility of a "true Christian" to fall away, and it is a lie, and is pure poison, evil from the pit, which can cause true believers unnecessary anguish.
Phil Johnson has an excellent sermon on this topic : The Vine and the Branches (Sermon Audio- approx 1 hr)
Previous posts on this topic:
Can a Truly Saved Person Fall Away
Can a Truly Saved Person Fall Away Part 2
Can a Truly Saved Person Fall Away Part 3
Can a Truly Saved Person Fall Away Part 4
There's a difference between having doubts which the Lord corrects and helps you with, and an all-out falling out and away from Him which is discussed a bit in comments section of this blog entry
Maturity in Christ: Fruit
The Great Falling Away
The Falling Away of the Church