What does Romans 8:30 mean?

In the previous verse, Paul wrote that God predestined those who are now in Christ to be conformed to Christ's image. He made this choice about us before the world was formed (Ephesians 1:4). God's purpose for our lives has ever and always been that we will become like Jesus. In some way, God both knew and chose those who would be saved, long before we even existed to make such a choice. The subtle details of what this means, and how God accomplished it, are part of a much larger debate. In the context of this specific passage, however, those debates are beside the point.

Now Paul writes that those God predestined for this purpose, He also called. Stated in reverse, God called every single person he predestined. As Paul uses the word in Romans, being "called" by God is about His breaking into our awareness of Him and drawing us toward Himself.

Next, God justified every single person He called. The first four chapters of Romans deal with the issues of God's justification. To be "justified" by God is to be made right with Him. We can never justify ourselves because of our sin, not even by following the law, since we can't keep the law (Romans 3:10, 23). We can only be justified through faith in Christ (Romans 5:1).

Finally, every person God justified, by faith in Christ, He then glorified. Paul writes this in the past tense, indicating that our glorification is as good as completed in God's eyes. However, Paul began this section in verses 18–19 by saying that all of creation is waiting for the children of God to be glorified. We are waiting for that, too, though our sure and confident hope is that it is coming in God's perfect timing.