From the very beginning, God sought a people who would live before Him without fear. He wanted His children to be at rest in body, soul and spirit by fully trusting in His promises. God called this "entering My rest.” So He led His people into a barren wilderness, without water, food or any source of sustenance. Giving Israel only His promise to keep them, His message to them was simply, "Have faith in Me.” He called them to place all their trust in Him to do the impossible for them.
According to the author of Hebrews, God’s people at that time never entered into His rest, because they didn’t trust in His promises (Hebrews 3:11).
In the passage about the fig tree, Jesus refers to an unnamed mountain:
"Whosoever shall say unto this mountain, Be thou removed, and be thou cast into the sea; and shall not doubt in his heart, but shall believe that those things which he saith shall come to pass; he shall have whatsoever he saith” (Mark 11:23).
Jesus was saying to His disciples, as well as to us today: "Unbelief in your heart is like a hindering mountain that cannot be moved. If it is not cast out, I cannot work with you.”
The fact is, Jesus was unable to perform miracles in a certain town because of the people’s unbelief:
"He did not do many mighty works there because of their unbelief” (Matthew 13:58).
The same holds true for Christ’s church today: wherever there is unbelief, He is unable to work. Unbelief is always the mountain that hinders the fullness of God’s revelation and blessing in His children.