What does Romans 9:23 mean?

Paul, making the case that God has and exercises the right to show mercy or not to humans as He pleases, has compared God to a potter. What if God, the potter, purposefully made some to be vessels of wrath, explicitly prepared for destruction? However, what if He endured with much patience those vessels even though He desired to show His wrath and power?

More specifically, Paul asks, now completing the thought, what if God endures those vessels of wrath with patience, not yet destroying them, in order to make known the riches of His glory for the vessels of mercy? He finished by stating that the vessels of mercy have been prepared beforehand for glory. That last thought fits with what Paul wrote in the previous chapter about all of those who are in Christ (Romans 8:31–39). God predestined, called, justified, and will glorify all who come to Him by faith in Christ.

Paul's main idea here, though, seems to be this: God's relationship to "vessels of wrath" somehow serves His purpose to reveal His glory to the "vessels created for mercy." He will use the destruction of the dishonorable vessels to accomplish His purpose of mercy for those in Christ.

Theological difference aside, we can take certain universal points away from this. Some vessels—some people—are destined for destruction and will suffer God's wrath, which all people deserve because of sin (Romans 3:10; 3:23). Other vessels—other persons—will be shown mercy, even though they also deserve wrath because of God's merciful work through Christ. However the choice is made, or how the details might work, God will call people to faith in Christ—He will elect, or predestine—anyone He wants to. He will hold all others responsible for not trusting in Christ. Not only is this just, it's also merciful, and entirely within His rights as the Creator. He is God.