When Israel had the opportunity to go up and possess the land the Lord gave them, instead of welcoming the opportunity they shied away from it. They saw some giants in their promised land and were terrified to face them because they looked bigger and stronger. However, these enemies were certainly no bigger or stronger than the enemies they had faced previously back in Egypt.
It appears whenever they face a new challenge; the blessings, deliverance, and miracles the Lord previously performed were a thing of the past and quickly forgotten. They developed a fear pattern that continued to plague them, and it kept resurfacing each time they faced a new challenge. No matter how many times the Lord proved He was almighty, and nothing was too hard for Him; this spirit of fear lingered in their lives.
For I am the LORD, I change not; Mal. 3:6
Jesus Christ the same yesterday, and today, and forever. Heb. 13:8