So when I heard a Bible teacher quote this verse and rightly interpret that the Restrainer is indeed the Holy Spirit, I was surprised when he followed that up with saying that the Holy Spirit will be removed from His dwelling within us believers and would return to how He operated before Pentecost, by merely being upon and not in the saint. He said that when the Restrainer is 'removed' the Church stays behind to face the antichrist.
"And now you know what is restraining, that he may be revealed in his own time. For the mystery of lawlessness is already at work; only He who now restrains will do so until He is taken out of the way. And then the lawless one will be revealed..." - 2Th 2:6-8a
That is a frightening and unbiblical thought. There are so many NT passages that show that the Holy Spirit is a guarantee of our redemption and that without the Holy Spirit, we are none of His.
"Now He who establishes us with you in Christ and anointed us is God, who also sealed us and gave us the Spirit in our hearts as a pledge. (down-payment) - 2 Cor 1:21-22
"Do not grieve the Holy Spirit of God, by whom you were sealed for the day of redemption." - Eph 4:30
"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, 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." - Eph 1:13-14
We've been sealed and God is not going to unseal us and leave us helpless to face the antichrist (a judgment upon a Christ-rejecting world) without the protection of His indwelling Spirit. I love how Chuck Smith used to put it -- No Groom is going to beat up the Bride before the wedding.
The point I am making is that no matter how impressive your favorite teacher might be -- don't let your guard down - test everything s/he teaches - hold fast to that which is good and scriptural. In this dark hour of the Great Apostasy, no man's teaching is to be accepted unless it passes muster with "thus saith the LORD." Remember the Bereans.
Keep on the alert!!
"But as it is written:
'Eye has not seen, nor ear heard,
Nor have entered into the heart of man
The things which God has prepared for those who love Him.'
But God has revealed them to us through His Spirit. For the Spirit searches all things, yes, the deep things of God. For what man knows the things of a man except the spirit of the man which is in him? Even so no one knows the things of God except the Spirit of God. Now we have received, not the spirit of the world, but the Spirit who is from God, that we might know the things that have been freely given to us by God." - 1 Cor. 2:9-12