The Apostle Paul was “caught up” to “the third heaven” (Paradise), where he heard things that he was not permitted to repeat. Paul did not know whether this experience took place “in the body or out of the body” but since John was “in the Spirit” when he was “caught up” it is reasonable to conclude that so was Paul.
An “out of the body” experience is not necessarily the same as being “in the spirit”, for if that were so we would have to be out of the body to be in the Spirit! How then could we “walk in the Spirit” and be “led by the Spirit” daily if we were “out of the body”? For Paul to have suffered his “infirmities” (physical weaknesses) he had to have been in his body.
Does this mean he was not then walking in the Spirit? No, it does not. In Romans chapter 8 and Galatians chapter 5, he makes it clear that the alternative to being “in the Spirit” is being “in the flesh” — living a self-serving, self-indulgent, sinful lifestyle.
I repeat, in Romans 8:9, Paul makes clear that we are not in the flesh (old life) if the Spirit is in us. He is saying that we can live as Jesus did if we count our old life as dead and ourselves as alive through spiritual rebirth and the cleansing bath of water baptism.
Being “in the Spirit” does not mean that we live an unreal, esoteric life, but rather one of victory over “the world, the flesh, and the devil”. Can we be more “in the Spirit”? Yes, we can! There are “deep things of God” — depths of spiritual understanding — and there are heights of spirituality. The thing to remember is that we don’t need to be “out of the body” to experience them.
We cannot live a purely spiritual life in our present mortal body, and to exclude all material things is to become “too heavenly to be of any earthly use”. (The opposite, which is “too earthly to be of any heavenly use” is also true.) We can “walk in the Spirit” in a mall or the aisles of a supermarket and be as much “in the Spirit” as we are in the aisles of a church.
That is, until the Holy Spirit rises from within us for a particular reason or comes upon us in a greater measure — in which case anything can happen! Ephesians 2:10 informs us that God’s “works” — everything that He will ever do — are foreknown to Him and have been from the foundation of the world. God is Eternal and foreknows everything. We, however, live in Time, which means that all we need to do is “walk” in the “works” that God from the beginning of the world prepared for us.
These “works” are the ones that Jesus said those who believe in him would do (John 14:12). We in the steps of Jesus when we walk in the will of God.
All this may seem a big ask, but the Apostle Paul writes that Titus “walked in the same spirit” as he did — the same attitude of mind, if you like — and so walked “in the same steps” (2 Corinthians 12:18). Likewise, to walk in the “same steps” as Jesus, we need only “walk in the same Spirit”. And, since we live in the Spirit, it is natural for us to walk in the Spirit!