The first three plagues in Egypt also touched the people of Israel, while the next six plagues did not (Exodus 8:18; Exodus 9:4, Exodus 9:6; Exodus 9:26; Exodus 10:23; Exodus 11:7), though no visible demarcation was laid on the Israelites to distinguish them from the Egyptians. With the tenth plague, however, the people themselves placed a mark on their doors indicating that they were God’s property through the blood of the lamb (and ultimately the Lamb of God) (Exodus 12:7, Exodus 12:23). In Ezekiel 9:4 a “man clothed in linen” travelled through the city of Jerusalem to “put a mark on the foreheads of the men who sigh and groan over all the abominations that are committed in it”; the rest of the inhabitants of the city would be destroyed. The apostle Paul speaks about the saints being “sealed with the promised Holy Spirit” (Ephesians 1:13; Ephesians 4:30). The Spirit, of course, is the Spirit of Jesus Christ. Only those bearing his mark, washed by his blood, can escape the judgment of God and “stand” in that day of divine wrath.
3 saying, “Do not harm the earth or the sea or the trees, until we have sealed the servants of our God on their foreheads.”