To live a life that is unshakeable you have to build it on something that is unshakeable. The Word of God, whether it be written, spoken, or revealed will never die. Though the grass withers and flowers fade His Word stands forever. If that is so according to 1 Peter 1:24 then His promises are unshakeable and forever. We can build our life on His promises because He will accomplish what He says He will do. When God speaks it, it will be done.