If you are saved, "do you not know that you are the temple of God and that the Spirit of God dwells in you? (1 Cor. 3:16) This is an awesome truth that God, in the person of the Holy Spirit, indwells those who believe that Jesus Christ paid the penalty for their sin. This is one of the great benefits of having a relationship with Christ in the here and now.
It is unfortunate but little attention is given to the Holy Spirit who is the third person of the Triune Godhead or Holy Trinity. Jesus Christ who is God the Son came to reveal God the Father to us and make it possible for our sins to be forgiven. When the Son went back to be at the right hand of the Father, He did not leave us as orphans, but, together with the Father, sent the Holy Spirit as a Helper (John 14:15).
It is a mystery which we are not meant to fully understand in this life how the One God is manifested in three persons but this is an important biblical doctrine that all Christians need to better understand. The Bible clearly presents God the Father, God the Son, and God the Holy Spirit with separate roles yet the three are one God.
If God is One, you would expect both the Father and Son to be indwelling believers as well. This truth is borne out in Scripture where it is often difficult to distinguish which person of the Trinity actually cohabits with believers' spirits. But if the Father and the Son are in the Holy Spirit (and visa versa) then they are all three in us if the Holy Spirit is in us. Jesus said, "If anyone loves Me, he will keep My word; and My Father will love him, and We will come to him and make Our home with him" (John 14:23).
The presence of the Holy Spirit within us is a guarantee of our salvation (Ephesians 1:13-14). Those that are saved abide in Christ as well as allow Christ to abide in them (John 15:4). "By this we know that we abide in Him, and He in us, because He has given us of His Spirit. And we have seen and testify that the Father has sent the Son as Savior of the world. Whoever confesses that Jesus is the Son of God, God abides in him, and he in God" (1 John 4:13-15). If you are saved, you have the Holy Spirit within you and have been baptized by the Spirit into the body of Christ (1 Corinthians 12:13).
Some people confuse the concept of being "baptized in the Spirit" from being "filled with the Spirit". Believers are only baptized once by the Spirit when they are saved but they are filled with the Holy Spirit when they act according to God's will. There should be many fillings of the Holy Spirit in the life of a believer.
The world has a "new age" concept of God which presents Him as an impersonal force that is in everything. This is a pagan pantheistic religion which is completely contrary to Scripture. Nothing is beyond the control of God, and God can be everywhere He wants but He does not permeate His entire creation. God is holy and does not dwell in unbelievers because of their corrupt nature. But His Holy Spirit does dwell in Christians because God sees us in our future sanctified condition.
The Holy Spirit helps us know God's will for us by prompting our human spirit and helping us understand the Bible. Jesus said, "the Helper, the Holy Spirit, whom the Father will send in My name, He will teach you all things, and bring to your remembrance all things that I said to you" (John 14:26). So we know we have the Holy Spirit dwelling in us if we are learning more about God.
The Holy Spirit can live within us because God sees us in our eternal, perfect state: "And you, who once were alienated and enemies in your mind by wicked works, yet now He has reconciled in the body of His flesh through death, to present you holy, and blameless, and above reproach in His sight" (Colossians 1:21-22). So God's Holy Spirit dwelling in us makes Him as close at hand as He can possibly be. God's presence within us makes it possible to have a relationship with Him.
As is the case with all relationships, communication must take place for there to be one. God speaks to us through the Scriptures, and we speak to Him in prayer. God also speaks to us in the thoughts He gives us and in other ways but all these must be consistent with Scripture or they are suspect. Following the prompting of the Holy Spirit makes it possible for us to say and do things that have eternal value. Learning to discern the voice of the Lord within us from our own natural self is an important part of our spiritual growth.
Getting to know the Lord is a life-long journey. There is more about Him than we can ever know but the closer our relationship is with Him, the better equipped we are to deal with the challenges we face in this life. And the closer we are to the Lord, the more we experience the "fruit of the Spirit" which is, "love, joy, peace, longsuffering, kindness, goodness, faithfulness, gentleness, self-control" (Galatians 5:22-23).
If you have not experienced the wonder of having the Holy Spirit in you, this can be remedied immediately where ever you are by simply yielding your life to Christ. Pray to the Father confessing your sinful condition and need to have Christ in your life. Acknowledge that you believe Jesus died on the cross to pay the penalties for your sins and that He rose from the dead as proof of eternal life. If you are sincere when you pray this prayer, you'll never regret it.