God tells us to avoid all uncleanness as a manner of life. (Ep 5:3) Abiding in uncleanness is a work of our old man, the flesh (Ga 5:19-21), so we’re to put it to death. (Col 3:5-6) He calls us to holiness (1Th 4:7) in our entire being: spirit, soul and body. (1Th 5:23)
God’s definition of holiness exists only in Torah, Mosaic Law, where He defines what’s unclean, what defiles us, and how to purify ourselves and separate ourselves unto Him. (Le 11:44)
Becoming unclean is simply part of living in this world; even doing God’s will can make us unclean. (Le 12:2) The focus is on how we respond to our uncleanness. Do we pursue abominable things (Le 11:10), heedless of our filth (Pr 30:12), enjoying uncleanness (2Pe 2:10) and neglecting the purification process God has prescribed? (Is 1:16) Or do we obey Him and continually pursue fellowship with Him, cleansing ourselves of all filthiness of the flesh and spirit, perfecting holiness in the fear of God? (2Co 7:1)
We can try to spiritualize this away to mean whatever we like, but if our new man delights in God’s Law (Ro 7:22) we’ll look for ways to obey Him as well as we can. In ignoring God’s prescription for physical cleansing, why would we pretend to be aligned with His design for spiritual purity? Those who aren’t acknowledging all their filth, cleaning themselves up wholistically, purifying themselves and separating themselves to God as a manner of life, have no part in God’s kingdom. (Ep 5:5)
YHWH gave us laws on personal hygiene to keep us healthy, free of disease and infection, to teach us how to respect ourselves and others, and to give us insight into spiritual dynamics. He calls us to live in purity, both in the flesh and in the spirit (1Co 6:20), pursuing holiness and faithfully cleansing ourselves of defilement and contamination because we belong to Him. (1Pe 1:14-16)
The physical dimension of uncleanness is tangible, and God’s prescription for it was written long before the sciences confirmed it’s value. Walking out physical holiness helps us understand the spiritual, to see how it works and ensure that we’re being cleansed of our sin (1Jn 1:7); both dimensions are essential in our walk with God.