Isaiah 43 speaks of the ransom that is paid for us.  God says in verse 3, for instance, that He has given Egypt as a ransom for us. 

All of this to say that we are worth something to God.  And why are you worth something to God?  Look in verse 7 for a clue:  "Everyone who is called by My name, and whom I have created for My glory, Whom I have formed, even whom I have made."  [These are the ones for whom He has paid the ransom, whom He has called forth.]

Do you see the implication?

God has called us by name.  He names us.  He knows us.
And we are created.  He has created us.  He is the Creator.
And what does verse 7 say the reason for our creation is?

We have a purpose statement instilled in this verse.
We have a purpose - We have a Lord.