R. A. Torrey argued from John 13:10; 15:3 that the disciples were regenerate before Pentecost. According to John 15:3 the disciples whom Jesus addressed were already sanctified ceremonially by their obedience to the Mosaic law. But the emphasis of v 3 is that they were sanctified by their association with Jesus (see John 13:3-11). They were set apart from the world by following Christ. They were then cleansed through the Word (John 15:3), but not yet by the Spirit. And they were instructed to remain in that condition by their obedience to the commands of Christ (John 15:10). They had renounced the world, submitted to the demands of discipleship, and had preached Christ.
All this had been a great help toward future fruit-bearing. Yet not all of them were clean. However, between John 13:10 and John 15:3 the disciples were purged of Judas. In John 15:3 katharos is the adjective form of the verb just used in v 2. As a verb kathairo means to cleanse or purge; to prune or trim clean. Its noun form is also used in 13:10. But while the disciples were set apart, pruned, and potentially clean, as in 13:10 and 17:19, through God’s revelation in Christ, they still needed the washing of regeneration and the purging of entire sanctification.
B. F. Westcott wrote that the spiritual work represented by this cleansing was potentially completed, but it remained that it should be realized by them [The Gospel According to St. John, p. 217]. Donald Bloesch argued that they were clean by virtue of being covered by the blood of Christ, but they were not actually clean. Even though Jesus washed their feet, that act symbolized their future cleansing through the blood. “They did not yet have regeneration because they were not yet baptized into the death of Christ (Mk 10:35-45)…They were cleaned proleptically by virtue of the word addressed to them. They were on the way to regeneration but not yet totally cleansed” [The Holy Spirit: Works and Gifts, pp. 306-307].
They would not bear the fruit of the Spirit nor have spiritually reproductive life until after Pentecost. Wesley said the apostles were clean before Christ died by Jewish faith, for the Holy Ghost was not then given [Works, 8:287]. Thus, Wesley concluded that “the faith through which we are saved … is not barely that which the apostles themselves had while Christ was yet upon the earth. … And herein does it differ from that faith which the apostles themselves had while our Lord was on earth, that it acknowledges the necessity and merit of his death, and the power of his resurrection” [“Salvation by Faith,” Sermon #1, 1.3, 5].