The Holy Spirit is God also (Acts 5:3-4; 1 John 5:7). Our bodies are the temple of the Holy Spirit which is in us/Christians (1 Cor. 6:19). But “how” does the Holy Spirit exist inside us? This is the question. The Holy Spirit is not “literally” inside anyone and never has been. The Holy Spirit dwells inside us the same way that Jesus does, figuratively or representatively, by faith through his word (Rom. 10:17; Eph. 3:17; compare Gal. 4:6). Our little temple bodies are too small for God to literally/physically dwell inside. Notice that the heaven and heaven of heavens (universe) and Solomon’s temple are/were too small for him too.
“But will God in very deed dwell with men on the earth? behold, heaven and the heaven of heavens cannot contain thee; how much less this house which I have built!” (2 Chr. 6:18).
“Thus saith the Lord, The heaven is my throne, and the earth is my footstool: where is the house that ye build unto me? and where is the place of my rest?” (Is. 66:1).
“Am I a God at hand, saith the Lord, and not a God afar off? Can any hide himself in secret places that I shall not see him? saith the Lord. Do not I fill heaven and earth? saith the Lord” (Jer. 23:23-24).
Additionally, our “body temples” occasionally have sin in them (1 Kg. 8:46; Eccl. 7:20; Rom. 3:9,10,23; 5:12; 1 John 1:8), which means God is not “literally” in us because he chooses not to dwell where sin is.
“Behold, the Lord’s hand is not shortened, that it cannot save; neither his ear heavy, that it cannot hear: But your iniquities have separated between you and your God, and your sins have hid his face from you, that he will not hear” (Is. 59:1-2).
Finally, if the Holy Spirit/God (Acts 5:3-4) was “literally” in us, it was would either be impossible for us to sin (which is not true), or the Holy Spirit would be sinning along with us when we do (which is not true).