Free-will doctrine – what does it? It magnifies man into God; it declares God’s purposes a nullity, since they cannot be carried out unless men are willing. It makes God’s will a waiting servant to the will of man, and the whole covenant of grace dependent upon human action. Denying election on the ground of injustice it holds God to be a debtor to sinners, so that if He gives grace to one He is bound to do so to all. It teaches that the blood of Christ was shed equally for all men and since some are lost, this doctrine ascribes the difference to man’s own will, thus making the atonement itself a powerless thing until the will of man gives it efficacy. Those sentiments dilute the scriptural description of man’s depravity, and by imputing strength to fallen humanity, rob the Spirit of the glory of His effectual grace: this theory says in effect that it is of him that willeth, and of him that runneth, and not of God that showeth mercy.
C.H. Spurgeon A Jealous God, Sermon 502, March 29, 1863