“They went out from us, but they were not of us; for if they had been of us, they would have continued with us; but they went out that they might be made manifest, that none of them were of us.”
but they went out that they might be made manifest,
The phrase “that they might be made manifest” shows God’s purpose in the fakers leaving the assembly of believers. God wants to draw a very clear line between truth and error. Their departure makes it very clear that they did not belong to the church. By leaving, they will not mislead genuine believers. Their departure unmasked the truth of who they were plainly. Error ultimately reveals itself.
The word “that” introduces a purpose clause. We now see God’s purpose in their leaving – to safeguard genuine believers against the deception of false religion. God’s purpose is to reveal false doctrine.
none of them were of us
John does not teach here that Christians cannot fall away. The issue here is the capacity to distinguish between genuine and false believers. Remaining in a congregation does not necessarily infer that a person is a genuine Christian, but it does indicate the possibility that he is a Christian. The indication of whether a person is a genuine believer is not the recitation of creed or holding to a formal membership but a true embracing of the essential truths of Christianity.
Some people use religion to deceive others.
A mark of heresy is a lack of perseverance in the things of God and with the people of God. The mark of a genuine believer is that he loves genuine believers.
1 Jn 3:14, “We know that we have passed from death to life, because we love the brethren. He who does not love his brother abides in death.”
2 Pet 2:21-22, 21 “For it would have been better for them not to have known the way of righteousness, than having known it, to turn from the holy commandment delivered to them. 22 But it has happened to them according to the true proverb: ‘A dog returns to his own vomit,” and, “a sow, having washed, to her wallowing in the mire.’”
We need to learn the truth that not everyone who speaks from the pulpit is a genuine believer. The hard reality is that there are apostates and fakers in the church. If we do not alert ourselves to this truth, then we make ourselves vulnerable to deception.
New converts are especially susceptible to being misled by false religion. There is a difference between the true and the false and between the saved and the lost. There are all kinds of people within the structural church.
Even the apostles did not recognize a phony in their midst. He was one of the original twelve apostles. Judas fooled them all except Jesus. He wormed his way into the group, but he was not truly a part of them spiritually. That is why he betrayed Christ.