Well, thank you so much, my dear friend, for such an excellent question! Actually, I wouldn’t say that the Holy Spirit “indwelled” people in OT times so to say; but He did “come upon” certain men of the LORD’s choosing such as prophets and kings, and some others, so that God’s Word and purposes might be revealed to men. You will recall 2 Peter 1:21: “For the prophecy came not in old time by the will of man: but holy men of God spake as they were moved by the Holy Ghost.” Now, I do want to make a distinction between the Holy Spirit “coming upon” a person, and the Holy Spirit “indwelling” a person. This ‘indwelling’ has a more permanent character. There is thus a difference between the operations of the Holy Spirit in OT times, as opposed to NT times considering those who are born again. In OT times, this provision might be given to godly men or even in some cases to ungodly men, mainly for the purposes of prophesy; but the retention of God’s Spirit was conditional upon man’s walking in obedience to God’s will.  The Holy Spirit would be taken away if a man walked in disobedience to the LORD. Now today, by way of contrast, for those who have been saved, the Holy Spirit actually indwells us on a permanent basis, bringing us new life. And the Spirit will never be removed as we wait for the trumpet call from above when Christ Jesus comes to take us home to be with Himself. If you read Ephesians 1:13 and 14, you’ll see that for believers: “…after that ye believed, ye were sealed with that holy Spirit of promise, Which is the earnest of our inheritance until the redemption of the purchased possession….” Thus, for true Christians today, the Holy Spirit being given to us at salvation is the sure promise that we are saved for all eternity by the shed blood of our Lord Jesus Christ, through faith in His finished work at Calvary. Indeed, no one can go to heaven unless the Holy Spirit “abides” in him (to abide is to dwell on a permanent basis). Please consider John 3:3-5 to learn more about being born again. In John 14:16-17 we read: ”And I will pray the Father, and He shall give you another Comforter, that He may abide with you for ever; Even the Spirit of truth; whom the world cannot receive, because it seeth Him not, neither knoweth Him: but ye know Him; for He dwelleth with you, and shall be in you.”

Now, I have said that in OT times, the Spirit of God might come upon a person, only to be taken away at a later time due to disobedience. Consider the case of King Saul in 1 Samuel 10:6-24. Samuel was sent to anoint Saul as king over Israel, and we see that the Holy Spirit came upon Saul, and he did prophesy (see also 1 Samuel 11:6). But Saul was disobedient to the LORD, and we read that the Spirit left him and came upon David instead (1 Samuel 18:12). In the book of Judges, we see a number of cases where the Holy Spirit came upon different ones in a time of Israel’s great need (see Judges 3: 10; Judges 6: 34; Judges 11:29). I would like in particular to draw your attention to the very interesting case of Samson, of whom we read, “The Spirit of the Lord began to move him at times” (Judges 13:25; 14:6, and 15:14). You can see from the account of his life and times that Samson did not always walk according to God’s will; but even though Samson lost his power, which clearly had been from the Holy Spirit, God still used Samson for His purposes in his final act where the power came back upon Samson.

Now, the Spirit of God was with King David, but after his sin with Bathsheba, and once his sin was made clear to him by Nathan the prophet such that David confessed his sin, and expressed his sorrow, he prayed (and justly so) that God would not remove the Holy Spirit from him (Psalms 51:11).

I’m certain that David realized that the Holy Spirit left King Saul, and probably knew that it was only by God’s Grace and mercy that he himself did not receive this same sad outcome. But, today for born again Christians, we would not ever need to pray such a prayer because the Holy Spirit “abides” in believers, or in other words, He remains in us (an “abode” is a permanent home or dwelling).

To summarize, the prophets and others according to the LORD’s will did indeed speak by the Holy Spirit in OT times, but if anyone of these failed to walk in obedience with the LORD, the Spirit would be taken away. On the other hand, born again Christians today do indeed have the Holy Spirit dwelling within them, and we never have to be concerned of losing the Spirit once we are saved.  (SF)  (571.3)