Questions arrive at my desk nearly every day, but I think the most serious question needing immediate response is about the Holy Spirit. Can the Holy Spirit leave me once I have received Jesus as my Saviour? The question started out a little differently than that, as it was asked about an Old Testament person (David) having lost the Holy Spirit and then having Nathan speak to him and the Holy Spirit returned.
    Let me preface my remarks with, The Holy Spirit is God, and though God has placed Himself in nice little niches or cubbyholes for our understanding, He, nevertheless, is God. We cannot limit Him nor can we tell Him, "You can't do that!" God is God and He can do what pleases Him. So, if the Holy Spirit came and left in the Old Testament that was His perrogative. However, in the New Testament in Acts 2:17 God had promised to pour out his Spirit upon all people. What God promises, God follows through on. I'll say more about that as you read further. The following is my written answer to that question.
    Let me start out by saying the Holy Spirit, before the Lord’s death, resurrection and assention, was not poured out over the earth. Jesus said, John 16:7-11 16:7 "Nevertheless I tell you the truth; It is expedient for you that I go away: for if I go not away, the Comforter will not come unto you; but if I depart, I will send him unto you. John 16:8 "And when he is come, he will reprove the world of sin, and of righteousness, and of judgment: John 16:9 "Of sin, because they believe not on me; John 16:10 "Of righteousness, because I go to my Father, and ye see me no more; John 16:11 "Of judgment, because the prince of this world is judged."
    During the dispensation of the old testament the Spirit of the Lord came upon whosoever he would and could depart; Consider 1 Samuel 16:14 "But the spirit of the Lord departed from Saul, and an evil spirit from the Lord troubled him." (Of course, we know that the evil spirit is Satin.)
    In 1 Samuel 16:13 "Then Samuel took the horn of oil, and anointed him in the midst of his brethren: and the Spirit of God came upon David from that day forward. So Samuel rose up, and went to Ramah." Which gives us an excellent view of the longevity of the Spirit. Further proof of David having the inbiding Spirit with him is found in: I Samuel 18:12-14 18:12 "And Saul was afraid of David, because the LORD was with him, and was departed from Saul. I Samuel 18:13 "Therefore Saul removed him from him, and made him his captain over a thousand; and he went out and came in before the people. I Samuel 18:14 "And David behaved himself wisely in all his ways; and the LORD [was] with him."
    Another view of the abiding Spirit is found in Hebrews 13:5-6 13:5 "[Let your] conversation [be] without covetousness; [and be] content with such things as ye have: for he hath said, I will never leave thee, nor forsake thee. Hebrews 13:6 "So that we may boldly say, The Lord [is] my helper, and I will not fear what man shall do unto me. When Paul wrote "He said, I will never ...." he was quoting from the Old Testament, more a compilation of thought than a particular verse. Consider the following: Exodus 33:12 "And Moses said unto the LORD, See, thou sayest unto me, Bring up this people: and thou hast not let me know whom thou wilt send with me. Yet thou hast said, I know thee by name, and thou hast also found grace in my sight. Exodus 33:13-15 11:15 "Now therefore, I pray thee, if I have found grace in thy sight, shew me now thy way, that I may know thee, that I may find grace in thy sight: and consider that this nation [is] thy people. Exodus 33:14 "And he said, My presence shall go [with thee], and I will give thee rest. Exodus 33:15 "And he said unto him, If thy presence go not [with me], carry us not up hence." Also: Deuteronomy 20:1 "When thou goest out to battle against thine enemies, and seest horses, and chariots, [and] a people more than thou, be not afraid of them: for the LORD thy God [is] with thee, which brought thee up out of the land of Egypt. Isaiah 43:1-3 43:1 "But now thus saith the LORD that created thee, O Jacob, and he that formed thee, O Israel, Fear not: for I have redeemed thee, I have called [thee] by thy name; thou [art] mine. Isaiah 43:2 "When thou passest through the waters, I [will be] with thee; and through the rivers, they shall not overflow thee: when thou walkest through the fire, thou shalt not be burned; neither shall the flame kindle upon thee. Isaiah 43:3 "For I [am] the LORD thy God, the Holy One of Israel, thy Saviour: I gave Egypt [for] thy ransom, Ethiopia and Seba for thee." Finally Matthew 28:18-20 28:18 "And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth. Matthew 28:19 "Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: Matthew 28:20 "Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, [even] unto the end of the world. Amen."
    Now, Could the Holy Spirit of God have left David? With all that has been said and a little tongue-in-cheek, The Holy Spirit could do anything He wanted to do. DID HE? No! There is something about the Holy Spirit that is unique. Though He will not leave, He will withdraw to a quiet place in your soul. Sinning grieves the Holy Spirit. And we are admonished, Ephesians 4:30 "And grieve not the holy Spirit of God, whereby ye are sealed unto the day of redemption." Grieving the Holy Spirit is hurtful to Him. But quenching is even worse. I Thessalonians 5:19 "Quench not the Spirit." Have you ever felt lead to speak to a person about their salvation and you put it off only to find that there was no next time? Throwing cold water on a fire kindled in your soul to do the Lord’s bidding is Quenching the fire of the Holy Spirit.
    David sure grieved the Holy Spirit and I’m sure He withdrew to give David over to his sinful path but we are not apprised of David’s inner turmoil (if any) and I feel the Holy Spirit was in there pitching twangs of guilt and wrong-doing. Though that I cannot prove but, I see how quickly he repented when Nathan did accuse him of his sin. It must have been preying upon his heart even before Nathan said anything. When Scripture declares the, "Spirit of God came upon David from that day forward," then the Spirit of God came upon David from that day forward.