They forgot the God who saved them, who had done great things in Egypt, (NIV) Psalm 106:21
The author of Hebrews writes that Moses, “persevered because he saw him who is invisible” (Hebrews 11:27). In contrast, the Israelites endured only when their circumstances were favorable. They forgot about the God who saved them. They forgot about the great things God did for them in Egypt and in route to the Promised Land. They were primarily governed by what they saw in front of them in their current circumstances rather than trusting in the invisible and eternal God.
Today many of us become occupied with outward circumstances instead of centering our attention on God. When our circumstances are favorable, we believe. But when things seem to go against us, we question and doubt that God is in control. Our world says that “seeing is believing.” But, God wants us to focus on the unseen and believe. Where’s your focus?