Everyone who is born again will endure to the end.

Ephesians 1:13-14 "

13 In Him, you also, after listening to the message of truth, the gospel of your salvation—having also believed, you were sealed in Him with the Holy Spirit of promise, 14 who is given as a pledge of our inheritance, with a view to the redemption of God’s own possession, to the praise of His glory."


1 John 2:19 " They went out from us, but they were not really of us; for if they had been of us, they would have remained with us; but they went out, so that it would be shown that they all are not of us."

The evidence that someone was never born again is that they did not endure to the end.

Matthew 7:21-23 "
21 “Not everyone who says to Me, ‘Lord, Lord,’ will enter the kingdom of heaven, but he who does the will of My Father who is in heaven will enter.22 Many will say to Me on that day, ‘Lord, Lord, did we not prophesy in Your name, and in Your name cast out demons, and in Your name perform many[a]miracles?’ 23 And then I will declare to them, ‘I never knew you; depart from Me, you who practice lawlessness.’"