Why did Jesus spend three years performing signs and miracles in Israel?
Jesus spent three years performing signs and miracles throughout the land of Israel to prove to the Jews who He really was. This follows Israel's historical pattern: when they saw the signs, they believed. The miracles were evidence of His true identity, given so the Jewish people would recognize Him.
Les explains that Moses did what God told him before Israel: he threw down the rod and it became a serpent, then performed another miracle, and they believed because they saw the signs. Les says this pattern ran all the way up through Israel's history. Therefore, if nothing else is remembered, the reason Jesus spent three years performing signs and miracles up and down the land of Israel was to prove to those Jews who He really was.