And though the soul of man is of a spiritual nature, and remains a spirit, notwithstanding the pollution of sin; yet it being defiled with the flesh, and altogether under the power and influence of the lusts of the flesh, it may well be said to be carnal or fleshly: hence "flesh", as it stands opposed to spirit, signifies the corruption of nature, Ga 5:17; and such who are in a state of unregeneracy, are said to be after the flesh, and in the flesh, and even the mind itself is said to be carnal, Ro 8:5.
And that which is born of the Spirit, is spirit: a man that is regenerated by the Spirit of God, and the efficacy of his grace, is a spiritual man; he can discern and judge all things of a spiritual nature; he is a fit person to be admitted to spiritual ordinances and privileges; and appears to be in the spiritual kingdom of Christ; and has a right to the world of blessed spirits above; and when his body is raised a spiritual body, will be admitted in soul, body, and spirit, into the joy of his Lord.
"Spirit" in the first part of this clause, signifies the Holy Spirit of God, the author of regeneration and sanctification; whence that work is called the sanctification of the Spirit, and the renewing of the Holy Ghost, 1Pe 1:2.