It is difficult, if not impossible, to determine from Paul’s Epistle to the Galatians, just what the Galatian believers thought the rite of circumcision would accomplish for them spiritually. We doubt that they knew themselves, but the Judaizers had come in among them and had captured their attention so that these, who had been so gloriously saved by grace, now “desired to be under the law” (Gal. 4:21). They did not deny the efficacy of the finished work of Christ, but they were interested — just interested — in submitting to a religious ceremony which would in itself be a denial of the all-sufficiency of His redemptive work (3:1; 5:2-4). Result: the blessing was already vanishing (5:14) and the Apostle had to warn them: “A little leaven leaveneth the whole lump” (5:9). You can’t admit a little leaven and expect it to stop there.
With the Corinthians it was rather a case of countenancing moral wrong. One of their members had been living in grievous sin. But then, their number was large, and he was just one, and the congregation as a whole abounded in spiritual gifts. Feeling quite satisfied with themselves, therefore, they simply overlooked this disgrace to the name of Christ. But listen to Paul’s — God’s — view of the matter:
“And ye are puffed up, and have not rather mourned, that he that hath done this deed might be taken away from among you” (I Cor. 5:2).
“Your glorying is not good. Know ye not that a lithe leaven leaveneth the whole lump?
“Purge out therefore the old leaven…” (Vers. 6,7).
In these days when both spiritual error and moral wrong are made so palatable, when apostate unbelief and worldliness are presented so appetizingly, we do well to take heed to the Spirit’s warning to quickly purge out the “little leaven” that threatens to permeate the whole loaf. source