Definition
Leaven (Greek: ζύμη, zumē) is a typological term used in the New Testament as an image for the pervasive working of sin and false teaching (1 Cor. 5:6-8; Gal. 5:8-9; Matt. 16:6). In George Warnock’s corpus leaven occupies a central hamartological position: the type of the Feast of Unleavened Bread — the feast that directly follows Passover — depicts the life free from sin that the believer is called to live on the basis of the atonement. The penetrating and spreading properties of leaven make it a fitting type for the working of sin in the congregation: a little leaven leavens the whole lump.
Usage in the corpus
George Warnock
Warnock works out the type of Unleavened Bread in detail as a hamartological summons: “The penetrating and spreading characteristics of leaven make it to be a fitting type of malice and wickedness in a believer or in an assembly.” He marshals three scriptural texts as converging witnesses: Paul to the Corinthians (1 Cor. 5:6-8: “purge out therefore the old leaven, that ye may be a new lump”), Paul to the Galatians (Gal. 5:8-9: the influence of the Judaisers), and Jesus’ warning (Matt. 16:6: the leaven of the Pharisees and Sadducees).
Warnock formulates the spiritual consequence: “To observe the Feast of Unleavened Bread, therefore is to live a life that is free from the corrupting influences of sin and the flesh.” Leaven/sin increases whenever the believer settles into self-complacency: “When an individual, an assembly, or a group of assemblies settles back in self-complacency, satisfied with their condition… stagnation immediately sets in, the leaven begins to function, and ‘malice and wickedness’ characterize the whole denomination.” [Warnock, The Feast of Tabernacles, Ch. 3]