God should be glorified even if He chooses NOT to use us! Our hearts should want Him to be glorified whether He chooses us or not! However, most Christian’s focus is for God to use them, while never thinking about God being glorified!
Our purpose on Earth is NOT to be used by God! God can use a donkey if He so chooses! (Numbers 22) People make being used by God their purpose because of insecurities and their desire to prove themselves and to impress others! Many Christians that have been active in their church for a long time will tell you everything that God used them for. However, more than likely you will never hear them mention any example of where God was glorified! This is a common mistake.
We are here to glorify God! Our very existence on this earth whether God uses us or not should glorify Him in every way! This should be the very desire of our hearts! God should be glorified in our lives even if He never asks us to do one thing for Him! Men/women put too much emphasis on serving God and being able to tell people what they have done – instead of God being glorified in their lives!