No born again believer ever leaves God. Those that leave were pretenders who never knew Him. The Holy Spirit does not hop in and out of people.
Ephesians 1:12-14 "…12 in order that we, who were the first to hope in Christ, would be for the praise of His glory. 13 And in Him, having heard and believed the word of truth— the gospel of your salvation— you were sealed with the promised Holy Spirit, 14 who is the pledge of our inheritance until the redemption of those who are God’s possession, to the praise of His glory.…"
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 miracles?’
23 And then I will declare to them, ‘I never knew you; depart from Me, you who practice lawlessness.’"
Hebrews 12:5-7 "…5 And you have forgotten the exhortation that addresses you as sons: “My son, do not take lightly the discipline of the Lord, and do not lose heart when He rebukes you.
6 For the Lord disciplines the one He loves, and He chastises everyone He receives as a son.” 7 Endure suffering as discipline; God is treating you as sons. For what son is not disciplined by his father?"
The confusion on this matter is that so many people hear people say they are "Christians" but later down the road they reject Christ as if they never had Him. That's because they never had Him in the first place.
People can only "act" so long until the pretense becomes burdensome. These are the people who give up the pretense and go back to their vomit. Judas was of this sort, he had tasted the good fruit but was never a believer, he hung out with those he thought he could fool but when the pressure became too much he bolted and betrayed.
There are many more pretenders today than there are authentic born again believers, its called "cultural Christianity."
Very religious but not born again!
Matthew 23:27-28
27 “Woe to you, scribes and Pharisees, hypocrites! For you are like whitewashed tombs which on the outside appear beautiful, but inside they are full of dead men’s bones and all uncleanness.
28 So you, too, outwardly appear righteous to men, but inwardly you are full of hypocrisy and lawlessness."