Romans 9 is the core of Calvinism's doctrine of irresistible grace in the eternal salvation and condemnation of individual people, yet this chapter isn't even about eternal salvation!

Paul's use of the potter and clay analogy is from Isaiah 29 that speaks of God's temporary hardening of Israel because of their sins. They blinded themselves with pride, so he blinded them further to ensure that his judgment would be carried out, with the intent that the nation would eventually repent and be restored.