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 - It is very likely that the time of the passover was now approaching, when the Church of Christ would be called to extraordinary acts of devotion, in commemorating the passion, death, and resurrection of Christ; and of this circumstance the apostle takes advantage in his exhortation to the Corinthians. See the Introduction, Section 12.
Not with old leaven - Under the Christian dispensation we must be saved equally from Judaism, heathenism, and from sin of every kind; malice and wickedness must be destroyed; and sincerity and truth, inward purity and outward holiness, take their place.
The apostle refers here not more to wicked principles than to wicked men; let us keep the feast, not with the old leaven - the impure principles which actuated you while in your heathen state; neither with the leaven of malice and wickedness, κακιας και πονηριας, wickedness, radical depravity, producing unrighteousness in the life; nor with the persons who are thus influenced, and thus act; but with the unleavened bread, αλλ' εν αζυμοις, but with upright and godly men, who have sincerity, ειλικρινεια, such purity of affections and conduct, that even the light of God shining upon them discovers no flaw, and truth - who have received the testimony of God, and who are inwardly as well as outwardly what they profess to be.
The word πονηριας, which we translate wickedness, is so very like to πορνειας, fornication, that some very ancient MSS. have the latter reading instead of the former; which, indeed, seems most natural in this place; as κακιας, which we translate malice, includes every thing that is implied in πονηριας, wickedness whereas πορνειας, as being the subject in question, see 1 Corinthians 5:1, would come more pointedly in here: Not with wickedness and fornication, or rather, not with wicked men and fornicators: but I do not contend for this reading.