Many portions in the book of Isaiah are clearly addressed to Israel. But I believe there can be a secondary application made to my life.
For example, in Isaiah 41, beginning with verse 9 God says, “You are my servant; I have chosen you and have not rejected you. So do not fear, for I am with you; do not be dismayed, for I am your God. I will strengthen you and help you; I will uphold you with my righteous right hand.”
I believe it is legitimate for me, one who has been chosen to serve God, to trust God to work in my life in a way similar to this promise to the Israelites whom He addressed in these verses as chosen servants. Compare Matthew 28:19-20 where Jesus encourages me not to fear because He would be with me.
Again, in Isaiah 41:9, I’m encouraged not to be dismayed because He is my God. His encouragement to not fear has to do with what He has called me to do in the future. His encouragement to not be dismayed has to do with trusting Him with what I have already done. We can be discouraged if what we have done didn’t turn out as we hoped it would.
Remember, God can make all things work together for good to those who love Him and are called according to His purpose (Romans 8:28).
If we are afraid of not being able to do all we are called to do in the future, we need to remember He will be with us. In fact He will strengthen and help us. He will uphold us with His righteous right hand.
With that kind of confidence in His presence and assistance, no matter what He calls us to do, we can succeed and bring Him glory. Trust Him.