Biblically Unitarians claim "the Bible does not teach that Jesus is God." Then by what means do you know or have any experience with Jesus Christ?

There's a lot of different threads in the OP that we could spend time picking apart. However, to address the main concern: you may know the Lord through love of God and one's fellowman

1 Corinthians 8:3 but if anyone loves God, he is known by Him.

1 John 4:7-8 Beloved, let’s love one another; for love is from God, and everyone who loves has been born of God and knows God. The one who does not love does not know God, because God is love.

Matthew 25:37-40 Then the righteous will answer Him, ‘Lord, when did we see You hungry, and feed You, or thirsty, and give You something to drink? 38 And when did we see You as a stranger, and invite You in, or naked, and clothe You? 39 And when did we see You sick, or in prison, and come to You?’ 40 And the King will answer and say to them, ‘Truly I say to you, to the extent that you did it for one of the least of these brothers or sisters of Mine, you did it for Me.’

Edit: in response to being flagged for not enough detail, I have provided everything needed. An explanation and supporting scripture references. Just because the Op is overly verbose does not mean it requires a lengthy response to answer it.

The answer is revealed by Jesus, who plainly explained how we are to live in a new Kingdom, prior to him being sent back by his Father and God. He lays out the truth in John 14

“Do not let your heart be troubled; believe in God, believe also in me. v1

Jesus *said to him, “I am the way, and the truth, and the life; no one comes to the Father except through me. v6

If you had known me, you would have known my Father also; from now on you know Him, and have seen Him. v7

The words that I say to you I do not speak on my own, but the Father, as He remains in me, does His works. 11 Believe me that I am in the Father and the Father is in me v10

And I will ask the Father, and He will give you another Advocate to be forever with you--the Spirit of truth. v6 WNT

I will not leave you as orphans; I am coming to you. After a little while, the world no longer is going to see me, but you are going to see me; because I live, you also will live. On that day you will know that I am in My Father, and you are in me, and I in you. v18

Jesus answered and said unto him, If a man love me, he will keep my word: and my Father will love him, and we will come unto him, and make our abode with him. v23

The holy spirit which Jesus' Father would send, is the means to having a true relationship. This the 'world' cannot have as they have the deceiving spirit of the devil residing within. Only God can rectify this default condition. All God's new covenant work is done through Jesus v10.

By this presence of God in us, we pray, we believe, we trust and obey - the core of relationship with God and Jesus is to trust and obey. The experience of knowing God is the love and grace that flows from the one true loving God.

This process is revealed in many examples where God filled His servants with His spirit in order to enable them to function without the limitations of their own corrupted spirit.

Then Moses said to the sons of Israel, “See, the LORD has called by name Bezalel the son of Uri, the son of Hur, of the tribe of Judah. 31And He has filled him with the Spirit of God, in wisdom, in understanding, in knowledge, and in all craftsmanship; 32to create designs for working in gold, in silver, and in bronze, 33and in the cutting of stones for settings and in the carving of wood, so as to perform in every inventive work.

John the Baptist, Paul etc also were given special spiritual connection with God and enabled to accomplish His purposes. This is similar to what happens when one accepts Jesus as their Lord, and through baptism, also receive this spirit in them.

Without this Godly spirit connection, there can be no relationship - based on trust and love - which allows and enables, belief and obedience.

Jesus being not God is crucial to all that he accomplished. He too, was led by God's spirit and trusted his Father to see him through to the bitter end of his mission - to be the Lamb who would save the world from sin and death. He proved it could be done - by being a man (John 8:40) like us in every respect Heb 2:17.

I have told you these things so that in me you may have peace. In the world you will have tribulation. But take courage; I have overcome the world!” John 16:33

Because Jesus was a man like us, who had the same God we all do (John 20:17) he overcame evil only with the spiritual support from his God. If he was God, this feat is rendered worthless and he actually overcame nothing.

how can Jesus Christ NOT be God if He dwells in every believer everywhere at all times?

Apart from the bible not telling us anything about Jesus being God, we are shown how the whole process works from the pages of Gen to Rev as God dwells in His people and animates them by His spirit to understand truth, believe and experience new life as John 14 explains in detail.

Answer derived in part from https://21stcr.org and similar sources.

Rather than add to the existing answer which addresses the initial line of questioning, the following is from the same source and amply addresses the new tack -

(OP) Clearly, to the inspired author of the Book of Romans, the "Spirit of God" and the "Spirit of Christ" are the same spirit. Furthermore for someone to be considered a Christian (ie."his") then this "Spirit of Christ" must "dwell in the believer. Who's "spirit" is the "Spirit of Christ"? Is it not Jesus Christ?

“This Jesus God raised up again, to which we are all witnesses. Therefore having been exalted to the right hand of God, and having received from the Father the promise of the holy spirit, he [Jesus] has poured forth this which you both see and hear.” (Acts 2:32-33)

Jesus is seen as the dispenser of the spirit. Not only is he the greatest prophet inspired by the spirit of God, not only is he the anointed by God of the spirit (to preach the gospel and heal people), but he is also the lord of the spirit who baptizes his followers in the spirit of God. Even so, this is still not all. Paul picks up where John left off and further develops the connection between the ascended Jesus and the spirit. Consider the chart below which enumerates some of the places that Paul speaks of the spirit:

• spirit dwells in the believer – Romans 8:9, 11; 1 Corinthians 3:16; 6:19; 2 Corinthians 1:22; Ephesians 2:22; 5:18

• spirit of Christ dwells in the believer – Romans 8:2, 9; 2 Corinthians 3:17[19]; Galatians 4:6; Philippians 1:19

• Christ dwells in the believer – Romans 8:9-10; 2 Corinthians 13:5; Galatians 2:20; Ephesians 1:23; 3:16-17; Colossians 1:27

Paul freely switches between these phrases as if they were synonymous. In order to demonstrate this, consider the texts below:

“For this reason I bow my knees before the Father, from whom every family in heaven and on earth derives its name, that He would grant you, according to the riches of His glory, to be strengthened with power through His Spirit in the inner man, so that Christ may dwell in your hearts through faith…” (Ephesians 3.14-17)

One of the functions of the spirit is to empower the Christian to have Christ dwell within them. The two (spirit & Christ) are intimately linked to each other in the experience of the NT saint.

“However, you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. But if anyone does not have the Spirit of Christ, he does not belong to Him. If Christ is in you, though the body is dead because of sin, yet the spirit is alive because of righteousness. But if the Spirit of Him who raised Jesus from the dead dwells in you, He who raised Christ Jesus from the dead will also give life to your mortal bodies through His Spirit who dwells in you.” Romans 8:9-11

This is remarkable. It is as if the spirit of God, the spirit of Christ, and Christ himself are all equivalent ways of speaking about the same essential truth. Paul does not focus on the ontological distinctions rather he sees the spirit primarily in functional terms in the experience of the Christian. From this perspective the spirit is Jesus. “The Spirit is now definitely the Spirit of Christ, the other Counselor who has taken over Jesus’ role on earth. This means that Jesus is now present to the believer only in and through the Spirit, and that the mark of the Spirit is both the recognition of Jesus’ present status and the reproduction of the character of his sonship and resurrection life in the believer.