The Greek ekkatharizō means to cleanse thoroughly or purge completely — the ek prefix intensifying the basic verb katharizō (to cleanse). Paul uses it in 1 Corinthians 5:7 regarding the removal of leaven from the household at Passover: 'Get rid of (ekkatharizō) the old yeast, so that you may be a new unleavened batch.' The command reflects both Passover ritual and spiritual renewal.
Paul's use of ekkatharizō in 1 Corinthians 5 grounds the call for church discipline in the Passover typology. Just as every trace of leaven was removed from Jewish homes before Passover (Exodus 12:15), the church must remove the 'leaven' of flagrant sin — 'malice and wickedness' — to be a community of 'sincerity and truth' (1 Corinthians 5:8). The standard is total, not partial, cleansing. Christ our Passover Lamb has been sacrificed; therefore we must be what we are — unleavened, pure, renewed.