You claim David was worried about God taking the spirit from him. I say, David was confessing his sins, he was convicted and prompted by the Holy Spirit, he was repentant and trusting in Christ, his Saviour, he was born again, he was a justified converted believer.
You speak of not being permanently indwelt as if you know these things. But yet, scripture does not seem to agree with you. For example, your familiar with John Ch:3?
Now there was a man of the Pharisees, named Nicodemus, a ruler of the Jews;this man came to Jesus at night and said to Him, “Rabbi, we know that You have come from God as a teacher; for no one can do these signs that You do unless God is with him.” 3 Jesus responded and said to him, “Truly, truly, I say to you, unless someone is bornagain he cannot see the kingdom of God.”
4 Nicodemus *said to Him, “How can a person be born when he is old? He cannot enter his mother’s womb a second time and be born, can he?” 5 Jesus answered, “Truly, truly, I say to you, unless someone is born of water and the Spirit, he cannot enter the kingdom of God. 6 That which has been born of the flesh is flesh, and that which has been born of the Spirit is spirit. 7 Do not be amazed that I said to you, ‘You must be born The wind blows where it wishes, and you hear the sound of it, but you do not know where it is coming from and where it is going; so is everyone who has been born of the Spirit.”
9 Nicodemus responded and said to Him, “How can these things be?” 10 Jesus answered and said to him, “You are the teacher of Israel, and yet you do not understand these things? 11 Truly, truly, I say to you, we speak of what we know and testify of what we have seen, and you people do not accept our testimony. 12 If I told you earthly things and you do not believe, how will you believe if I tell you heavenly things? 13 No one has ascended into heaven, except He who descended from heaven: the Son of Man. 14 And just as Moses lifted up the serpent in the wilderness, so must the Son of Man be lifted up, 15 so that everyone whobelieves will have eternal life in Him. John 3.
If it is according to you and your teachings, why did Jesus say to Nicodemus, "You should have known this. You should know that you need to be born of the spirit." :10
Yet, we see in John 7:39, But this He said in reference to the Spirit, whom those who believed in Him were to receive; for the Spirit was not yet given, because Jesus was not yet glorified.
So what you have is a mess. In John 7, you have scripture saying the spirit is not yet given, but in John 3, you have Jesus saying to Nicodemus, being a teacher, that he should have known that one has to be born again and that which is born of the Spirit is spirit, etc...
Yes, there is this newness to Pentecost.