It is reported commonly that there is fornication among you, and such fornication as is not so much as named among the Gentiles, that one should have his father's wife.
Fornication — The original word implies criminal conversation of any kind whatever.
His father's wife — While his father was alive.
 And ye are puffed up, and have not rather mourned, that he that hath done this deed might be taken away from among you.
Are ye puffed up? Should ye not rather have mourned - Have solemnly humbled yourselves, and at that time of solemn mourning have expelled that notorious sinner from your communion?
 For I verily, as absent in body, but present in spirit, have judged already, as though I were present, concerning him that hath so done this deed,
I verily, as present in spirit — Having a full (it seems, a miraculous) view of the whole fact. Have already, as if I were actually present, judged him who hath so scandalously done this.
 In the name of our Lord Jesus Christ, when ye are gathered together, and my spirit, with the power of our Lord Jesus Christ,
And my spirit — Present with you.
With the power of the Lord Jesus Christ — To confirm my sentence.
 To deliver such an one unto Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus.
To deliver such an one — This was the highest degree of punishment in the Christian church; and we may observe, the passing this sentence was the act of the apostle, not of the Corinthians.
To Satan — Who was usually permitted, in such cases, to inflict pain or sickness on the offender.
For the destruction — Though slowly and gradually.
Of the flesh — Unless prevented by speedy repentance.
 Your glorying is not good. Know ye not that a little leaven leaveneth the whole lump?
Your glorying — Either in your gifts or prosperity, at such a time as this, is not good. Know ye not that a little leaven - One sin, or one sinner.
Leaveneth the whole lump — Diffuses guilt and infection through the whole congregation.
 Purge out therefore the old leaven, that ye may be a new lump, as ye are unleavened. For even Christ our passover is sacrificed for us:
Purge out therefore the old leaven — Both of sinners and of sin.
That ye may be a new lump, as ye are unleavened — That is, that being unleavened ye may be a new lump, holy unto the Lord.
For our passover is slain for us — The Jewish passover, about the time of which this epistle was wrote, 1 Corinthians 5:11, was only a type of this. What exquisite skill both here and everywhere conducts the zeal of the inspired writer! How surprising a transition is here, and yet how perfectly natural! The apostle, speaking of the incestuous criminal, slides into his darling topic,-crucified Saviour. Who would have expected it on such an occasion. Yet, when it is thus brought in, who does not see and admire both the propriety of the subject, and the delicacy of its introduction?
 Therefore let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness; but with the unleavened bread of sincerity and truth.
Therefore let us keep the feast — Let us feed on him by faith. Here is a plain allusion to the Lord's supper, which was instituted in the room of the passover.
Not with the old leaven — Of heathenism or Judaism. Malignity is stubbornness in evil. Sincerity and truth seem to be put here for the whole of true, inward religion.
 I wrote unto you in an epistle not to company with fornicators:
I wrote to you in a former epistle — And, doubtless, both St. Paul and the other apostles wrote many things which are not extant now.
Not to converse — Familiarly; not to contract any intimacy or acquaintance with them, more than is absolutely necessary.
 Yet not altogether with the fornicators of this world, or with the covetous, or extortioners, or with idolaters; for then must ye needs go out of the world.
But I did not mean that you should altogether refrain from conversing with heathens, though they are guilty in some of these respects.
Covetous, rapacious, idolaters — Sinners against themselves, their neighbour, God.
For then ye must go out of the world — Then all civil commerce must cease. So that going out of the world, which some account a perfection, St. Paul accounts an utter absurdity.
 But now I have written unto you not to keep company, if any man that is called a brother be a fornicator, or covetous, or an idolater, or a railer, or a drunkard, or an extortioner; with such an one no not to eat.
Who is named a brother — That is, a Christian; especially if a member of the same congregation.
Rapacious — Guilty of oppression, extortion, or any open injustice.
No, not to eat with him — Which is the lowest degree of familiarity.
 For what have I to do to judge them also that are without? do not ye judge them that are within?
I speak of Christians only. For what have I to do to judge heathens? But ye, as well as I, judge those of your own community.
 But them that are without God judgeth. Therefore put away from among yourselves that wicked person.
Them that are without God will judge — The passing sentence on these he hath reserved to himself.
And ye will take away that wicked person — This properly belongs to you.