Consider these Israelites. They saw a multitude of miracles performed by God through His servant Moses and on occasion through Aaron. They experienced the water turn to blood and frogs hop all over the place. They experienced the eerie, penetrating darkness that pervaded all of Egypt. They experienced the division between Goshen and Egypt, and they knew God spared them from the remaining plagues.
They knew something was "working" in their lives. They could see it occurring when the flies were all over Egypt except in Goshen. They saw it happen through five other plagues. They experienced it again on Passover night when the firstborn of Egypt were killed, but the firstborn of Israel, shielded by the blood on their doorposts and lintels, were not. Did they not see that?
Did they not spoil the Egyptians? Did they not leave Egypt? Did not God part the Red Sea before their eyes and drown all the Egyptian army in its waters? Did they not eat manna supplied from heaven every day for forty years in the wilderness? Did they not see water flow like a river out of solid rock? Did they not see quail blown toward them so that they had all the meat they could eat?
They saw the glory of God descend on Mount Sinai. They felt the earth shake under their feet. They saw the pillar of fire and cloud. They saw the glory of God rest upon the Tabernacle when it was set up. Nevertheless, every single one of them, except for two men and their families, perished!
Is seeing believing?
The Israelites never really saw God in those works. What they physically saw did not produce the spiritual faith that enables one to see God, because, as these verses explain, the one whose eyes are opened must voluntarily respond. The Israelites never responded positively to God.
The Christian's responsibility is to respond to God's calling through acts of faith. The apostle reminds the Hebrews of the deadly seriousness of their situation. God's calling is not indiscriminately handed out to anyone who might happen to see or read. It is a personal invitation (John 6:44). God has addressed it specifically to us!
These verses also contain a warning: Since Israel did not enter into God's rest, someone else will, because God will fulfill His purpose. The Christian ought not to think that he will automatically enter it in Israel's place.