Sincerity and truth

1 Cor 5:1-13
Therefore let us keep the Festival, not with the old bread leavened with malice (惡意) and wickedness, but with the unleavened bread of sincerity and truth.
Not to associate with sexually immoral people - not at all meaning the people of this world who are immoral, greedy and swindlers, or idolaters. But now I am writing to you that you must not associate with anyone who claims to be a brother or sister but is sexually immoral or greedy.
What business is it of mine to judge those outside the church? Are you not to judge those inside? Expel the wicked person from among you.
Festival: Passover, Jesus Chris is crucified on the cross
Why?
Christian should love others and love sinner, but any brother or sister is sexually immoral or greedy, we should not associate with them, and expel the wicked person from church. Don't let the old bread leaven with wickedness affect us.
It is the righteousness of Christian. When we have learn the word of the Lord, we should know what is right and wrong, all the evil mind and  behavior need to be removed.
Sincerity and truth is the characters of Christian life. Unleavened bread.
Old bread leavened: malice, wickedness, sexually immoral, greedy.
How?
Be sincerity and truth without sexually immoral and greedy, malice.