Why did God keep the flies from crossing into Goshen?
God kept the flies from crossing into Goshen to prove His power and make Himself known as the Lord in the midst of the earth. He drew an invisible line around Goshen, putting a division between Israel and Egypt and marking Israel as His set-apart covenant people.
Les teaches that God was proving His point and showing the Egyptians that if He could draw an invisible line around Goshen, even the insects would not cross it. God said He would draw that line so Goshen would have no flies, “that they may know that I am the Lord in the midst of the earth.” He also put a division between His people Israel and Egypt, a sign setting apart the children of Israel from the Egyptians. Les points out that all through Israel’s history they were told, “You’re different… a set apart people… the covenant people,” and were to have nothing to do with the pagan Gentiles. He sees a New Testament analogy in 2 Corinthians 6, where Paul gives the same directions, and cites Romans 15:4 that these Old Testament things were written for our learning. Just as God separated Israel from Egypt, He places a line of demarcation between the believer and the world, because no one can serve two masters.