It was always the plan from the beginning.
The Spirit hovered over creation, and God walked among man in the cool of the day, and so He has always wanted His Spirit to be present and dwelling in us. It has always been the plan. Even when we messed it up, the invitation has remained the same: come nearer. “Let us dwell in the house of the Lord”. Resist the urge to run away in fear or to reject Him heartlessly.
But in the Old Testament, the Holy Spirit could not inhabit inside a person because man on the inside was unclean and holy. It was only after Jesus appeared on the earth, died and resurrected that made it available for us to be cleansed and holy from the inside! So, in the Old Testament, the people of God were invited to a physical place called a tabernacle, temple or synagogue. In that place they can come into the Presence of God and enjoy Him. In the Old Testament, you had to go to church!
Now since Jesus had come, the invitation that was from the beginning of time can be given out again: “Come, let Me dwell within you.” Since the New Testament, instead of us being invited from the outside, instead of inviting you to come to a physical tabernacle, temple or place of worship, this invitation is from within us. God wants to make you His dwelling place. Since the New Testament, you get to be The Church.
For one who is born again and surrendered to the lordship of Jesus Christ, you are now the dwelling place and temple of the Holy Spirit. You have already come into His Presence because He dwells in you. All we need to do is not tune Him out. He has made you holy and perfected you, so live it, being holy and perfect. He has cleansed you, so remain pure and clean. He has loved you all this time, so love Him back. He has given you a powerful voice and testimony, so use it powerfully and without fear.
God’s Holy Spirit dwells in you, so let Him out and show His effect to the world. You are the Church, the Dwelling Place of the Holy Spirit.