It is not so much the Spirit in a believer so much as the believer in the Spirit like being in a place. The woman of Samaria at the well was concerned she did not worship in Jerusalem but Jesus prophesied the place to worship would soon be 'in the Spirit'. John was in this sense 'in the Spirit' on Patmos when Jesus' angel came to him. Jerusalem on earth is a heavy rock and weighs on the soul and likewise the Spirit of God is a heavy rock and when He weighs on your soul you are in the Spirit. Judah of old was tethered to Jerusalem for site of worship whereas Israel and later Samaria broke the tether. Jesus foretold a new tether in worship tethering the worshipper not to a site but to the Spirit of God for worship. Spirit and truth. This must be why the disciples had to remain tethered to Jerusalem until the new tether for worship came - the Holy Spirit from above. At Pentecost. See how blind Israel tribes became compared to Judah who stayed in Jerusalem's vicinity and worshipped at the Temple. So the Spirit keeps believers who worship attached to Him in their spirit from becoming blind and wandering from truth. In practice this tethering works by gifts of the Holy Spirit whose leadings and resulting revelations of truth and into truth along with other manifestations of the Holy Spirit such as a still small voice like Elijah and Peter heard all is to be kept for reference and guidance and a prompting for the inner man and spirit which brings back that sense of being attached to the holy and to truth and to Spirit in worship and meditation. This is how I discerned then wrote this. And of course the Spirit attaches us when our spirit is connected to Him (to the seven Spirits) to the throne of God in the exalted heavenly Zion. Mixing metaphores it seems to me our own spirit is like a lightning conductor conducting the Holy Spirit to us once God gives us a visit from Him when we are believers of His message. (I could sense myself under influence of influence of and tether to that weighty rock of the Spirit when those things came to me. It is real.) Here is my own testimony that might help some to believe and understand. I wanted spiritual gifts all my life and eventually God heard my prayers and a local leader back in athe mid nineties took me to a church where he said I would receive what I so earnestly sought. At the meeting a leader gave a message at the mic in tongues. So beautiful the words and not babble but real angelic sentences in a definite language but out of this world. (Years later I learned a technical term for it is xenoglossia.) I had a feeling of pressure on me which was the Holy Spirit and as each sentence was spoken it inspired pictures and English words in my mind which were a glorious prophesy about the glory of the power of the Lord Jesus' name and authority and how trees bud and produce leaves by it. I'd never heard such things. Then the speaker stopped and started speaking n English and his words were the very words I heard. I reckon this was interpretation of tongues. It is a gift. It is not itself tongues but was great and certainly the Holy Spirit. Since then I heard Him speak to me too and prove to me it was Him. I never spoke in tonges but it sure is the Holy Spirit God gave me. Here is how He proved He is real. Years later I was arguing on LinkedIn and had a lie down to think what I had been saying and contemplate things about God. I thought about how so many times the enemies I made at work and in day to day life got judged by God and bad things happened when they became a serious danger to me. It dawned on me that this was peculiar and as if surely an angel was guarding me. It popped into my mind that there was a verse in a Psalm (in the Bible scriptures) that might explain this but I could not think where it came from and wished it were confirmed to me that this was indeed what explained my experiences. "The Angel of the LORD encamps around those that fear Him to deliver them in times of trouble". Moments later a kind of voice of words spoken directly into my mind said simply "Daniel 3". So because it was so clear and striking I went to the lounge to see my Bible to look up Book of Daniel chapter 3. This Bible was one I was not at all familiar with having been given it as a gift. There was no mention in Daniel 3 until right near the end where the word "Angel" has a margin reference next to it. I looked up the reference and what did it say? I guessed already. A reference to the Psalm where it said "The Angel of the LORD encamps around those that fear Him to deliver them". So I knew this was an actual Spirit who gave me the simple words "Daniel 3" and so wisely proved to me that He was not a figment of my imagination. Now after years meditating on and pondering in my heart what the Spirit says over time to me I realise first hand that the Father (God) is wanting me and each disciple to have it from Him Himself that He regards Jesus Christ the Son of Man as His own Son who is righteous enough and faithful and true enough for the Father to say it with certainty and own Him for sure as His Son and wants it to be that we too become what He cam call His children through what Christ has done and does and will do and by our obedience in puttting away what is in our behaviour that is akin to God's enemy Satan the enemy of what is right.
