Sarkikos (G4559) describes something controlled by or belonging to the sarx (flesh) β human nature in its unredeemed, self-centered orientation. Paul uses it to contrast two modes of existence: living according to the flesh (sarkikos) versus living according to the Spirit (pneumatikos). The contrast is not physical vs. non-physical but Spirit-led vs. self-led.
1 Corinthians 3:1-3 stings: 'I could not address you as people who live by the Spirit but as people who are still worldly [sarkikoi]... you are still worldly [sarkikoi]. For since there is jealousy and quarreling among you, are you not worldly?' The diagnostic for sarkikos living is not obvious immorality but division, envy, and rivalry. The flesh shows itself most in Christian community fractures.