The passage
      v6. The Corinthians were proud of their egalitarian acceptance of those from all walks of life, yet "their headiness put them in imminent danger of being spoiled by fermentation", Fee. They should know well enough the proverb "a little leaven leavens the whole batch of dough", or as we sometimes put it, "a bad apple spoils the whole barrel". The NIV "yeast" is incorrect. The ancients didn't use much yeast, rather they kept back a small piece of dough to mix with next weeks dough. This rather foul fermented mixture then leavened next weeks bread. At the feast of Unleavened Bread the cycle was broken for both health reasons and religious symbolism.
      v7. Extending the imagery of the feast of the Unleavened Bread, Paul applies the idea of cleansing the house of fermented material prior to preparing the new unleavened bread for the festival. In this way he again calls on the church to cast out the incestuous member, as with all evil, so that they might be a cleansed people for God. Paul immediately qualifies this imperative in case it encourages nomism - the notion that obedience secures God's favour. Paul reminds his readers that they are already this new dough, because of Christ's sacrificial death on their behalf. They are "the new batch" (loaf) because Christ has become the "Passover Lamb", sacrificed for them, achieving their eternal forgiveness and freedom for a new life in the Spirit. We can summarize Paul's ethical imperative for believers as: "be what you are."
      v8. As the seven day festival of the Passover is kept by excluding leaven from the home, so the church is to exclude evil from its life. We are to be what we are, a holy living people. We should live as people set free from "malice and wickedness", free from every form of evil. Celebrating our unleavened state Paul describes as living in "sincerity and truth." These ideals concern the motivation behind our behavior. They are about being authentic, open and honest, rather than into theatre, deception, sham...

Be what you are
      Congregations, as well as individual believers, are under constant pressure to modify the person we are in Christ, so that we might better fit in with our present culture. We may even be proud of our egalitarian spirit, or our pop-culture relevance. Such may give us acceptance in the wider community, even improve the marketability of our church, but it will also sow the seeds of our destruction.
      In Christ's death our old life died and in his resurrection we were made alive. We are now a new creation, a new being, designed for eternal service. In this little moment of our life we are privileged to be that "new man" in Christ. So, corruption has no place in the life of either the Christian community or the individual believer.

      How shall we deal with corruption?

      i] Cast out the evil. For the individual believer this is no easy matter. Wrestling with darkness costs us. Still, we must face down evil and do our best to defeat it. Passivity in the face of sinfulness is not a Christ-like quality.
      When it comes to the Christian fellowship, facing down evil in the congregation, exposing it and seeking to remove it, is extremely difficult. Who is to decide the sinfulness of a member? Ultimately, only the congregation can pass judgement on the evil of a fellow member. Even then it could only happen where the members are in community, where genuine fellowship exists in the congregation. It certainly can't happen in institutionalized Christianity where the ministry team functions as part of an organized power structure.

      ii] Claim victory over evil. The imperative in Christian ethics is based upon an indicative. Through His death and resurrection, Christ has cleansed us and carried us perfected into the presence of God. This is the indicative, the way we are. The imperative calls on us to be what we are. The "what we are" exposes evil as an unnatural intrusion into our lives. Evil has no place there; Christ has defeated it. When we recognize this we are empowered for the fight.

      iii] Affirm the positive. Affirm "purity and faithfulness". Rather than present a sham of goodness, let us openly and honestly display the person we now are in Christ - fallen but recreated. We now have no reason to hide our weakness, no reason to hide our failures.

v7
      ekkaqarate (ekkaqairw) aor. imp. "get rid of" - purge out, clean out, cleanse. The aorist possibly suggests a command to perform a specific act, although the imperative often rules out any sense of duration. The prefix to the verb suggests both motion and intensity and therefore the urgency of the action, cf. Thiselton. "Clean out every bit [of the old infection]", Phillips.
      iJna + subj. of verb to-be. "that [you may be a new batch without yeast]" - that [you may be a new/fresh lump of dough]. Probably introducing a purpose clause, "in order that", although consequence is always possible, "with the result that", eg. CEV. Paul is heading toward a sanctification by obedience position, so he quickly qualifies this statement in the next phrase. The sense of 7a is "be what you are" - an imperative based on an indicative.
      neon adj. "a new [batch without yeast]" - new, fresh, young [mixture]. As of unleavened bread, "then you will be like fresh bread made without yeast", CEV.
      kaqwV este azumoi "as you really are" - as / insomuch as / as indeed you are unleavened [uninfected]. The adjective "unleavened" may be functioning as a substantive and therefore, verbal in form. In which case the phrase is "you are unleavened loaves" (loaves understood).
      kai gar "for" - indeed for. Explaining how it is that the Corinthians are a new batch of dough. Another possibility, "for besides", Barrett.
      to pasca "Passover lamb" - the passover. The NIV (as with NRSV, REB, Moffatt, NAB... ) assumes, and probably correctly, that Paul has in mind Christ's role as the Passover lamb, rather than just the Passover festival as a whole. "Christ is for us the Passover lamb, sacrificed for our deliverance", Barclay.
      etuqh (quw) aor. pas. "has been sacrificed" - was sacrificed. Aorist indicates a once-and-for-all sacrifice. "Has already been sacrificed", CEV.