Isaiah 35 contains a prophecy that is designed to make us say, “I can’t wait to get there!”  The key to understanding the prophecy is noting both the picture of our preferable future (vv. 1-2, 5-10) and instruction for those of us who must wait (vv. 3-4).  In this case, the instructions of vv. 3-4 become a condition to arriving at our final destination in the new heavens and new earth.  To reject the instructions is equal to trusting in some other deliverance–some form of idolatry.  Isaiah has been challenging God’s people to trust God wholly in order to be assured of inheriting the Kingdom.  The Gospel can be communicated as you explain the concept of redemption found in vv. 9-10.  Once again, one angle to the Cross can be seen through a contrast with v. 4’s statement: “He will come and save you.”  God did do that on the Cross when He did not come and save His Son.