Isaiah 1:16

Wash you. Sin results in moral pollution and spiritual decay. When David sinned, his prayer was, “Wash me, and I shall be whiter than snow” (Ps. 51:7). He recognized the defilement of sin and asked God to give him a clean heart (v. 10), and his prayer was heard. Every sinner is in need of moral purification; his heart must be cleansed of its moral corruption. God calls upon the sinner to wash his heart of wickedness (Jer. 4:14), to cleanse his hands of iniquity (James 4:8). He promises to write His law in the heart (Jer. 31:33) and to cleanse man from all unrighteousness (1 John 1:9). Isaiah called for Jerusalem to put on her beautiful garments, for the time was coming when the unclean would no longer enter there (Isa. 52:1). John declared that nothing that defiles will in any wise enter into the Holy City (Rev. 21:27). The lesson Isaiah endeavored to impress upon Israel was that God, “the Holy One of Israel,” requires holiness of His people.

Cease to do evil. God called upon His people to cease from sin. He was holy, and they were to be holy. Evil must be put out of the life of every child of God. Sin will not exist in the pure atmosphere of heaven, and all who enter there will wear the garments of righteousness.