In these verses, 2 important dichotomies present themselves. The first is a distinction between groups of people (a dichotomy from without); the natural person (ψυκικος, the material or unspiritual person, one who is void of the indwelling the the Holy Spirit) and the spiritual person (πνευματικος, the spiritual person being indwelt and guided by the Holy Spirit). In these verses the difference between these groups of people is how they respond to spiritual truths: either by misundertanding or examining respectively. This difference is based on their position to the work of the Holy Spirit in their lives as either rejection or acceptance. Coming to faith appropriates the work of the Spirit in our lives which fundamentally changes us…from natural to spiritual.
Equally important though is the dichotomy from within. This is the dichotomy in a spiritual person in which their σαρκινος (ie the flesh…the term for the remnant of the natural person within the spiritual person that is now in the process of learning to yield to the Holy Spirit) has become enamored of natural things again . In Paul’s interaction with the Corinthian believers, this flesh had been rearing its ugly head and needed to be confronted so that the church would again align its actions and activities with the precepts of the spiritual man as directed by the Holy Spirit.
This implies that we need to understand when encountering “natural” people and directly ask for the enlightening intervention of the Holy Spirit in their lives (John 16). It also means believers need to regularly examine themselves to build a growth from flesh acting up against the Spirit to the flesh in subjection to the Spirit.